Diesel fuel pump on '51 TDI 1.9

[Martin J]

Dear All

 

My Octavia packed up today. I had just started out on the dual carriage way, flicked the cruise control on at 75MPH and then the power just died. Fortunately, I was able to freewheel down an exit lane out of harm's way.

 

The Green Flag man did his checks and found there was insufficient fuel flow. He concluded that the fuel pump (mechanical) had probably failed with an outside chance the fuel filter might be the problem. I checked my records and found the fuel filter was last changed in May 13.  I spoke with a VAG specialist and he thought it was either the pump or the 'uplift' pump in the fuel tank and unlikely to be the fuel filter.

 

The car is a '51 plate and has 167,000 on the clock. Is this about normal for a car of this age and mileage?

 

I have booked the vehicle in for a thorough diagnostics check. Depending on the result, I have to decide whether to get it fixed or call it day.

 

Bit upset. Feels a bit like an old friend. It has never let me down and is in excellent condition for the age.

 

Any views on this are appreciated.

 

Thanks

 

Martin

 

 

[Martin J]

PS - Footnote to my original post.

 

The car has done 27,000 in the four years since the fuel filter was last changed.

 

Thanks

 

Martin

[Peterj222]

Hi Martin, Pretty sure the pre- PD engines with the mechanical rotary pumps did not have a lift pump in the tank so not likeley to be that! What engine code do you have in your car? The old pumps were pretty bullet proof unless used with contaminated diesel or bio fuel but some of them had electronic components that could fail.

 

Peter

[Martin J]

Peter

 

The engine number is ASV299452ASV

 

Thanks for your interest

 

Martin

[Peterj222]

That will be the 110 then

I doubt very much it would be the filter blocked although always worth draining it through the drain on the bottom in case youve got some water in the fuel (apparantly Tescos are well known for this!)

Firstly though get it scanned for fault codes as I am wondering wether it is coincidence that you say it died as soon as you turned the cruise control on, so maybe electrical???

If it is the internals in the mechanical pump it may not show up as a fault but at least you have a starting point.

A mate of mine owned a cab company and ran a fleet of vehicles with these engines and had no pump problems and they all went on to 300k plus miles no problems....but theres always the chance.

Having said that even if it is the pump you can source a second hand one for peanuts now and they are not rocket science to change ... cam belt off is the worst bit.

Also worth checking that you havent got a blockage somewhere between the tank and filter / filter and pump check none of the pipes have been kinked or damaged.

Let me know how you get on... you cant be far from me as I am just outside of Aylesbury so give me a shout if you need any help.

Peter

PS once you get a bit of air in the system on these engines they are an absolute pig to start so if you drain the filter make sure you refill it with diesel before you try to start it or it will just turn over forever, although you can bleed them by backing off the nuts on top of the injectors and spinning it over (This will also give you an idea if you are getting any diesel up to the injectors)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Martin J]

Peter

 

I am in Buckland next to Aston Clinton!

 

That is a really helpful post particularly as you have come to the same conclusion as me. Electrical. At the time it happened, all the warning lights came on and then everything died. Also, even stranger, the fuel warning light was on before the incident. 50 miles left in the tank. I was on my way to Hemel and usually top up at the Shell service station while I am over there. After gliding to a halt on the hard shoulder on the roundabout, I tried starting it and noticed that the fuel gauge had jumped from just above the red warning blob to nearly a third full. That is peculiar and must surely be an electrical problem. The Green Flag man added another gallon of diesel as a precaution with no change as to be expected. This is a problem 'related' to fuel flow not fuel shortage. I also note that when the car died I could hear a slight whining sound winding down. There are a lot of air bubbles in the fuel pipe when is being cranked over.

 

Since you are a local man, is there anyone in this area that you would recommend to do work on these cars?

 

Martin

 

[Peterj222]

 I am just down the road in Wendover! Afraid I cant recommend anyone locally as Im not originally from round here and tend to do all of my own maintenance and repair work (when I have the time!!)

Dont know if you have checked the fuses but looking through my owners manual fuses numbers 10,29 and 44 seem to be for diesel engine electronics and number 32 for diesel pump injection control?? worth a check before spending money!!

Peter

[Martin J]

That's great.

 

I'll let you know how I get on.

 

Thanks

 

Martin

[Martin J]

Peter

 

I ended up checking every fuse in the box mounted at the end of the dashboard on the driver's side.

All OK.

 

However, during last week we had a downpour and the sunroof was left open on tilt.

 

The following day I noticed traces of water/damp around the area close to the hand grabs where the grey material covering the roof area inside joins the plastic sleeves on the front pillars. It dried out after a day or so. There are drain holes either side but the water must have had backed up at some point or been restricted by gunk inside the pillars. I feel sure this must be related.

 

We have the above, the engine dying when the cruise control was activated and the fuel gauge registering wasy above the level prior to the engine failure.

 

Could it be a short circuit that has not actually caused any fuses to blow? I did wonder whether damp got into the fuse box somehow as a result of the downpour but there are no signs of any moisture.

 

Martin

[Peterj222]

Sent you a PM Martin.

[Martin J]

The following codes came up on a basic diagnostics check.

 

18062

17965

P1557

P1256

 

That's it. This was not a full VAG diagnostics test at this stage.

 

I am now searching the internet for similar symptoms which might relate to the above.

 

Martin

[kentphil1]

Here are your last 3 codes for info, the first relates to instrument cluster codes being stored, probably the other 3.

 

http://wiki.ross-tech.com/wiki/index.php/17965/P1557/005463

 

http://wiki.ross-tech.com/wiki/index.php/17965/P1557/005463

 

http://wiki.ross-tech.com/wiki/index.php/17664/P1256

 

Hope it helps

[Martin J]

kentphil1

 

Thanks for the links. Really helpful.

 

I am beginning to build a picture here.

 

Just to get the last one out of the way which I do not think is relevant to the specific problem here but useful nevertheless. I have noticed that the engine temperature has been running slightly cooler than normal. I assumed the thermostat needed replacing. Also, the idle speed on startup can sometimes fluctuate and can get as high as 1000RPM before settling down and returning to normal idle speed.

 

We tried a 'booster pack' startup today as the battery was close to flat after the session with the Green Flag recovery man when it broke down. No sign of catching at all.

 

I now need to do some extra research on the links to the 17965 code concerning boost etc.

 

Do you have a link to the code 18062?

 

Martin

 

 

 

 

[nige8021]

18062 is oil temp/level sensor defective

[kentphil1]

19 hours ago, Martin J said:

kentphil1

 

Thanks for the links. Really helpful.

 

I am beginning to build a picture here.

 

Just to get the last one out of the way which I do not think is relevant to the specific problem here but useful nevertheless. I have noticed that the engine temperature has been running slightly cooler than normal. I assumed the thermostat needed replacing. Also, the idle speed on startup can sometimes fluctuate and can get as high as 1000RPM before settling down and returning to normal idle speed.

 

We tried a 'booster pack' startup today as the battery was close to flat after the session with the Green Flag recovery man when it broke down. No sign of catching at all.

 

I now need to do some extra research on the links to the 17965 code concerning boost etc.

 

Do you have a link to the code 18062?

 

Martin

 

Here you go,

 

As above, 18062 is oil sensor issue

 

Quote

Fault table   Note t  On vehicles 08.98 ? different fault codes are displayed with the same or similar text. Select the required text in the fault table according to the fault code. t  If “Info in literature” appears in the display of the vehicle system tester, look for the text required in the fault table under the fault code. t  The fault table is ordered according to the fault code on the left. t  Explanations on fault types (e.g. interruption/short-circuit to earth) → Operating instructions of vehicle system tester. t  If parts are output as faulty: First test all of the cables and plug connections to these components as well as the earth cables of the system according to the current flow diagram. Only if no fault is detected here should the part be replaced. This applies particularly if the fault is shown as sporadic (SP).

Display -V.A.G 1552-
Fault number			Possible cause of fault	Possible effects	Fault elimination
old		new
00513		16705
Engine speed sender -G28-
	implausible signal		t  Sender disc bent or loose t  Clearance of rotary speed sender/sensor rotor too great t  Metallic swarf on engine speed sender -G28- t  Line interruption of the screening t  -G28- defective	t  poor starting t  irregular engine running, misfiring t  increased idling speed t  Preheating warning light flashes t  reduced performance t  No display on rev counter t  Engine does not start	–  Remove noise insulation and test sender disc. –  Check engine speed sender → Chapter.
	no signal	16706	t  -G28- defective t  Line interruption or short-circuit
			t  Line interruption of the screening
00519		17563
Intake manifold pressure sender -G71-
	Short circuit to positive		t  Short circuit to positive t  -G71- defective	t  reduced performance	–  Check intake manifold pressure sender -G71- → Chapter. –  Inspect intake system for leaks.
	Open circuit/Short-circuit to earth	17564	t  Line interruption or short-circuit to earth t  -G71- defective
	Supply voltage	17565	t  Line interruption or short-circuit
		17566	t  Line interruption or short-circuit
00522		17663
Coolant temperature sender -G62-
	Short circuit to earth		t  -G62- defective t  Line short-circuit to earth	t  Black smoke when starting t  Engine preheating not operational t  preheating always occurs for approx. 20 seconds	–  Test coolant temperature sender → Chapter.
	Open circuit/Short circuit to positive	17664	t  -G62- defective t  Open circuit or short circuit to positive
00527		17568
Intake manifold temperature sender -G72-
	Short circuit to earth		t  -G72- defective t  Line short-circuit to earth	t  Engine preheating not operational	–  Test intake air temperature sender → Chapter.
	Open circuit/Short circuit to positive	17569	t  -G72- defective t  Open circuit or short circuit to positive
00532		18008
Supply voltage
	implausible signal if necessary		t  Control unit was fitted on with the ignition switched on		–  Erase fault memory and observe vehicle → Chapter.
Voltage supply tml. 15
	Voltage too low		t  Line interruption or short-circuit t  No voltage when iginition on (Terminal 15)	t  Engine does not start t  Engine stoppage	–  Testing voltage supply for diesel direct injection system → Chapter. –  Testing voltage supply on terminal 15 → Current flow diagrams and Fitting locations.
			t  Engine control unit -J248- defective t  Diesel direct injection system relay -J322- defective		–  Replace control unit → Chapter. –  Testing voltage supply for diesel direct injection system → Chapter.
00539		17570
Fuel temperature sender -G81-
	Short circuit to earth		t  -G81- defective t  Line short-circuit to earth	t  reduced performance t  Increased emission levels	–  Check fuel temperature sender → Chapter.
	Open circuit/Short circuit to positive	17571	t  -G81- defective t  Open circuit or short circuit to positive
			t  Disconnect plug connection for injection pump	t  several faults stored t  Engine stoppage	–  Test plug connection for injection pump.
00542		17653
Needle lift sender -G80-
	Short circuit to earth		t  -G80- defective t  Line interruption or short-circuit	t  Preheating warning light flashes t  rough engine running t  reduced performance t  Increased emission levels	–  Test needle lift sender → Chapter.
	implausible signal	17654	t  Fuel feed interrupted (has been): Tank empty, feed line or filter clogged, system draws in air	t  possible fault 00550 injection commencement control, control difference stored t  Misfiring, Jerking	–  Test fuel system.
			t  (Sporadic) line interruption to fuel shut-off valve	t  Engine stoppage t  Misfiring	–  Test cable connection and plug connection on the injection pump.
			t  Sender disc of engine speed sender bent or loose	t  Mirfiring exactly at 3000 rpm	–  Remove noise insulation and test sender disc.
			t  -G80- defective	t  Misfiring, jerking (in particular at a higher engine speed)	–  Replace needle lift sender.
			t  Injection pump defective	t  Fault 01268 metering adjuster -N146- stored t  irregular engine running, misfiring t  no throttle after trailing throttle	–  Replacing injection pump → Chapter.
	Open circuit/Short circuit to positive	17655	t  -G80- defective t  sproadic line interruption (cable fracture)	t  Preheating warning light flashes t  Misfiring, Jerking t  reduced performance	–  Test needle lift sender → Chapter.
00550		17656
Injection commencement control
	Control difference (deviation)		t  Injection commencement N.O.K.	t  Loss of power at a higher engine speed t  Engine starts poorly t  Increased emission levels	–  Dynamically testing and setting the commencement of injection → Chapter
			t  Adjustment path of the injection pump blocked (dirt, swarfs)	t  Loss of power at a higher engine speed	–  Inspecting the injection-timing range → Chapter.
			t  Engine stalled (within the last 50 starts)		–  Erase fault memory, observe vehicle → Chapter.
			t  Fuel feed interrupted (has been): Tank empty, feed line or filter clogged, system draws in air	t  possible fault 00542 needle lift sender implausible signal stored	–  Test fuel system.
			t  Line interruption to commencement of injection valve - N108-	t  Engine jerks when idling, because the commencement of injection is constantly on “early”	–  Testing commencement of injection valve → Chapter.
				t  possible several faults stored	–  Test fuses.
			t  Injection valve -N108- worn	t  no constant commencement of injection possible during “basic setting” (display field 2 fluctuates, more than 10 displays) t  irregular engine running, poor performance	–  Replace commencement of injection valve.
00553		16485
Air mass meter -G70-
	implausible signal		t  Engine stalled (within the last 50 starts)		–  Erase fault memory, observe vehicle again → Chapter.
			t  Battery weak	t  reduced performance t  displayed air mass in measured value block	–  Check the battery.
			t  sporadic line interruption (cable fracture) to needle lift sender -G80-	t  Misfiring, Jerking t  possible Fault 00542 needle lift sender, input open or interruption/short circuit to positive	–  Test needle lift sender → Chapter.
			t  Air filter blocked t  Vacuum piping of exhaust gas recirculation is incorrect or mechanical exhaust gas recirculation valve is always open	t  irregular idling, poor performance	–  Inspect intake system –  Inspect vacuum hoses → Chapter.
			t  Air mass meter faulty	t  Poor performance. jerking	–  Test air mass meter → Chapter.
	Open circuit/Short-circuit to earth	17552	t  -G70- defective t  Line interruption or short-circuit to earth	t  reduced performance t  possible Black smoke when accelerating from low speeds
	Short circuit to positive	17553	t  -G70- defective t  Open circuit or short circuit to positive
	Supply voltage	17554	t  Line interruption or short-circuit
00575		17958
Intake manifold pressure (charge pressure)
	Control difference (deviation)		t  Hoses interchanged, not fitted on, clogged, leaking t  Pressure box of turbocharger defective t  Charge pressure control solenoid valve -N75- faulty	t  sudden performance interruption t  reduced performance	–  Test charge pressure → Chapter. –  Check charge pressure hose → Chapter.
00625		16885
Vehicle speed signal
	implausible signal		t  Line interruption between speedometer sender -G22- and dash panel insert t  -G22- defective t  Speedometer -G21- defective t  Line interruption between dash panel insert and engine control unit	t  CCS not operating t  Air conditioning system not operational t  possible load change jolts t  Speed display N.O.K.	–  Testing the speed signal → Chapter. –  Test speedometer sender → Electrical System → Rep. Gr.90.
Vehicle speed signal		17948
	Signal too high
00626		18024
Glow period warning light -K29-
	Short circuit to positive		t  Short circuit to positive	t  Glow period warning light not operational
	Open circuit/Short-circuit to earth	18025	t  Line interruption t  Bulb defective	t  Glow period warning light not operational	–  Test glow period warning lamp → Chapter.
			t  Short circuit to earth	t  Glow period warning light lights up and remains lit
00668		18009
Onboard voltage terminal 30
	implausible signal		t  Diesel direct injection system relay -J322- jams t  Diesel direct injection system relay -J322 defective	t  Engine does not start (safety deactivation)	–  Testing voltage supply for diesel direct injection system → Chapter.
00671		-
CCS switch -E45-
	undefined switch status		t  E45 defective t  Line interruption or short-circuit	t  Cruise control system is deactivated	–  Testing cruise control system → Chapter.
00741		-
Brake pedal monitoring
	implausible signal		t  Switch is incorrectly set t  Line interruption t  -F- or -F47- defective t  Fuse defective t  both brake lights defective	t  Preheating warning light flashes t  Fuse or brake light defective	–  -F- and -F47- testing and adjusting → Chapter. –  Test fuse and brake light.
00765		17762
Modulating piston movement sender -G149-
	Electrical fault in the circuit		t  10-pin plug connection for injection pump disconnected t  Injection pump defective t  Line interruption or short-circuit	t  several faults stored t  Engine stoppage t  Poor vehicle handling t  Engine stoppage t  Preheating warning light flashes	–  Test plug connection for injection pump. –  Test modulating piston movement sender → Chapter.
00777		18039
Accelerator pedal position sender -G79-
	Signal too high		t  Line interruption t  -G79- defective (idling switch)	t  Safety control to approx. 1100 rpm t  no throttle t  Preheating warning light flashes t  increased idling speed	–  Check accelerator pedal position sender → Chapter.
	Supply voltage	18040	t  Line interruption or short-circuit
	implausible signal if necessary	18047	t  Line interruption t  -G79- defective (idling switch)
Accelerator pedal position sender 1/2 -G79+G185-1)
	implausible signal
	Short circuit to positive	-	t  Short circuit to positive t  -G79- defective

 

1) Incorrect fault text display. The correct display is: Accelerator pedal position sender -G79-.

 

Display -V.A.G 1552-
Fault number			Possible cause of fault	Possible effects	Fault elimination
old		new
01028		-
Blower relay -J323-
	Open circuit/Short-circuit to earth		t  Line interruption t  Relay -J323- defective t  Short circuit to earth	t  Fan afterrun without function t  Radiator fan always on	–  Test signal for radiator fan → Chapter.
	Short circuit to positive	-	t  Short circuit to positive	t  Fan afterrun without function
01044		18020
Engine control unit incorrectly coded
			t  invalid control unit coding	t  Preheating warning light flashes	–  Code the control unit → Chapter.
01117		17911
Load signal for alternator terminal DF
	implausible signal		t  Line interruption or short-circuit t  AC generator defective t  Voltage regulator defective	t  Engine preheating not operational	–  Testing the wiring –  Inspect AC generator → Current flow diagrams and Fitting locations.
01180		-
Engine/air conditioning compressor electrical connection
	Short circuit to positive		t  Short circuit in the wiring	t  reduced vehicle acceleration, when the air conditioning system is on	–  Testing signals from/to the air conditioning system → Chapter.
01193		19460
Low heat output relay -J359-
	Open circuit/Short-circuit to earth		t  Line interruption t  Low heat output relay -J359- defective	t  Engine preheating not operational t  Engine preheating always on	–  Test wiring → Current flow diagrams and Fitting locations. –  Test low heat output relay → Chapter.
			t  Short circuit to earth
	Short circuit to positive	19459	t  Short circuit to positive	t  Engine preheating not operational
01194		19462
High heat output relay -J360-
	Open circuit/Short-circuit to earth		t  Line interruption t  High heat output relay -J360- defective	t  Engine preheating not operational t  Engine preheating always on	–  Test wiring → Current flow diagrams and Fitting locations. –  Test high heat output relay → Chapter.
			t  Short circuit to earth
	Short circuit to positive	19461	t  Short circuit to positive	t  Engine preheating not operational
01237		17945
Fuel shut-off valve -N109-
	Malfunction (mechanical fault)		t  -N109- defective, leaktight or jams	t  reduced performance t  Engine stoppage	–  Check -N109- → Chapter.
	Open circuit/Short-circuit to earth	17946	t  -N109- defective t  Line interruption or short-circuit to earth	t  Engine stoppage	–  Test wiring → Current flow diagrams and Fitting locations.
01262		17954
Solenoid valve for charge pressure control -N75-
	Short circuit to positive		t  Short circuit to positive	t  reduced performance t  Charge pressure too low	–  Inspecting charge pressure control solenoid valve → Chapter.
	Short circuit to earth	17955	t  Short circuit to earth	t  reduced performance t  Charge pressure too high
	Open circuit/Short-circuit to earth	17957	t  Line interruption t  Solenoid valve defective	t  reduced performance t  Charge pressure too low
01265		17810
Exhaust gas return valve -N18-
	Short circuit to positive		t  Short circuit to positive	t  no exhaust gas recirculation
	Open circuit/Short-circuit to earth	17849	t  Line interruption t  Solenoid valve defective	t  no exhaust gas recirculation	–  Testing exhaust gas recirculation valve → Chapter.
			t  Short circuit to earth	t  too much exhaust gas recirculation t  reduced performance, black smoke
01266		18026
Glow plug relay -J52-
	Short circuit to positive		t  Short circuit to positive	t  Glow Plug System not operating	–  Test glow plug relay -J52-.
	Open circuit/Short-circuit to earth	18027	t  Line interruption t  Relay defective	t  Glow Plug System not operating	–  Test glow plug relay and wiring → Current flow diagrams and Fitting locations.
			t  Short circuit to earth	t  Glow Plug System constantly on
01268		17969
Metering adjuster -N146-
	Control difference (deviation)		t  Injection pump defective t  Line interruption or short-circuit	t  Poor vehicle handling t  Engine stoppage t  Preheating warning light flashes	–  Test metering adjuster → Chapter. –  Replacing injection pump → Chapter.
	upper limit value	17970	t  Metering mechanism adjusted	t  Jerking, loss of power
	lower limit value	17971	t  Metering mechanism adjusted	t  Black smoke t  irregular idling
01269
Commencement of injection valve -N108-		17659
	Short circuit to positive		t  Short circuit to positive	t  Engine jerks when idling, because the commencement of injection is constantly set to “early”
	Open circuit/Short-circuit to earth	17660	t  Line interruption (fuse) t  Valve defective	t  Engine jerks when idling, because the commencement of injection is constantly set to “early”	–  Testing commencement of injection valve → Chapter.
				t  possible several faults stored	–  Test fuse.
			t  Short circuit to earth	t  Loss of power, because the commencement of injection is constantly set to “late”	–  Testing commencement of injection valve → Chapter.
01282		19561
Changeover valve for intake manifold flap -N239-
	Open circuit/Short-circuit to earth		t  Line interruption t  Changeover valve for intake manifold flap defective	t  hard engine switch-off impact	–  Test the change-over valve for intake manifold flap → Chapter.
	Short circuit to positive	19560	t  Short circuit to positive
16500		-
Coolant temperature sender -G62-
	implausible signal		t  Coolant temperature sender -G62- supplies implausible signal caused by loose contact or corrosion due to humidity in the connector	t  Cold-start difficulties at very low temperatures t  Poor driveability during warm-up t  Increased fuel consumption t  Increased emission levels	–  Read measured value block, display group 007 → Chapter. –  Coolant temperature sender -G62- → Chapter.
			t  Signal input in engine control unit defective (control unit defective)		–  Replace engine control unit → Chapter.
			t  Coolant regulator defective		–  Check coolant regulator → 1.9 ltr./81 kW Engine, Mechanics → Rep. Gr.19.
16955		-
Brake light switch -F-
	implausible signal		t  Brake light switch defective t  Line interruption or short-circuit to positive or earth between the brake light switch and the engine control unit	t  Brake light does not light up t  Engine speed fluctuations during braking	–  Test brake light switch and brake pedal switch → Chapter.
17811		-
Exhaust gas recirculation system			t  Exhaust gas recirculation valve -N18- defective	t  Exhaust gas recirculation system not operating	–  Testing exhaust gas recirculation valve → Chapter.
	Control difference		t  Exhaust gas recirculation potentiometer -G212- defective	t  Mixture adaptation not operational	–  Inspect exhaust gas recirculation valve → 1.9 ltr./81 kW Engine, Mechanics → Rep. Gr.26.
17931		-
Crash signal from airbag CU
	implausible signal		t  Fault in the airbag system	t  Airbag warning light lights up	–  Test airbag → Body Work → Rep. Gr.01.
17964		-
Boost-pressure control
	Regulating limit not reached		t  Fault in charge pressure control t  -N75- defective	t  Poor vehicle handling t  reduced performance	–  Inspecting charge pressure control solenoid valve -N75- → Chapter. –  Check charge pressure control → 1.9 ltr./81 kW Engine, Mechanics → Rep. Gr.21.
17965		-
Boost-pressure control
	Regulating limit exceeded		t  Fault in charge pressure control t  -N75- defective	t  Poor vehicle handling t  reduced performance	–  Inspecting charge pressure control solenoid valve -N75- → Chapter –  Check charge pressure control → 1.9 ltr./81 kW Engine, Mechanics → Rep. Gr.21.
17977		-
CCS switch -E45-
	implausible signal		t  CCS switch defective t  Line interruption	t  CCS not operating	–  Testing cruise control system → Chapter. –  Reading measured value block 006 → Chapter.
17978		-
Engine control unit blocked
			t  Manipulation attempt t  Start attempt with unauthorised ignition key t  Engine control unit not adapted to immobilizer	t  Engine starts and stops immediately	–  Adapt engine electronics control unit to immobiliser → Electrical System → Rep. Gr.90.
			t  Short-circuit in communication cable t  fault in the immobilizer system		–  Test immobiliser → Current flow diagrams and Fitting locations.
			t  Immobilizer control unit defective/missing t  Engine control unit incorrectly coded		–  Code engine control unit → Chapter.
18044		-
Data bus drive
	missing message from airbag control unit		t  Datalines faulty t  an ABS fault is present	t  Poor vehicle handling	–  Test data bus → Chapter. –  Test airbag control unit → Body Work → Rep. Gr.01.
18050		-
Read out fault memory of the airbag control unit
			t  Fault in the airbag system	t  Airbag warning light lights up	–  Test airbag → Body Work → Rep. Gr.01.
18058		-
Data bus drive
	Missing message from combiinstrument		t  Datalines faulty t  wrong or defective dash panel insert t  incorrect or defective engine control unit	t  Poor vehicle handling	–  Test data bus → Chapter.
18061		-
Read out fault memory of the ABS control unit			t  Fault in ABS control unit	t  no vehicle dynamic control t  TCS not operational t  MSR not operational	–  Check ABS control unit → Chassis → Rep. Gr.45.
18062		-
Read out fault memory of the combi-instrument			t  Oil level and oil temperature sender -G266 - defective	t  Oil level warning light lights up	–  Check oil level and oil temperature sender -G266- → Current flow diagrams and Fitting locations.
18065		-
Air conditioning system inlet/outlet
	Short circuit to positive		t  Short circuit in the wiring	t  reduced performance	–  Check air conditioning system → Chapter.
18067		-
Radiator fan control 1
	Short circuit to positive		t  Short circuit to positive	t  Fan afterrun without function	–  Check blower relay -J323- → Chapter.
18080		-
Radiator fan control 1
	Open circuit/Short-circuit to earth		t  Line interruption t  Relay defective	t  Fan afterrun without function	–  Check blower relay -J323- → Chapter.
			t  Short circuit to earth	t  Radiator fan always on
18090		-
Data bus drive
	implausible signal from ABS control unit		t  Databus lines to ABS control unit interrupted	t  no vehicle dynamic control t  TCS not operational t  MSR not operational	–  Test data bus → Chapter.
18259		18057
Data bus drive
	Missing message from ABS control unit		t  Faults in the databus lines to ABS control unit	t  no vehicle dynamic control	–  Check databus lines to engine control unit for open circuit or short-circuit → Current flow diagrams and Fitting locations.
			t  Fault in ABS system		–  Check ABS control unit → Chassis → Rep. Gr.45.
18262		18056
Data bus drive
	Hardware defective if necessary defective		t  Faults in the databus lines to ABS control unit	t  no vehicle dynamic control	–  Check databus lines to engine control unit for open circuit or short-circuit → Current flow diagrams and Fitting locations.
			t  Fault in ABS system		–  Check ABS control unit → Chassis → Rep. Gr.45.
65535		16989 17795 18048
Control unit defective			t  Control unit internally defective	t  Poor vehicle handling t  Engine stoppage t  Preheating warning light flashes	–  Replace control unit → Chapter.

 

 

 

 

 

[Martin J]

Thanks everyone.

 

It all helps with the diagnosis and joining up the dots.

 

Think I will probably have to get the car relayed to a VAG expert for more detailed and practical tests.

 

Martin

 

 

[Martin J]

Preliminary checks show the cam belt and turbo appear to be OK.  My hunch is that sediment has collected at the bottom of the fuel tank over time and has caused a fuel blockage. The fact that the fuel gauge jumped from just above the red low zone to nearly a third of a tank suggests the possibility that some of this sediment may have also caused an artifical pressure reading.

 

Off to an independent VAG man as soon as he has a spare slot.

 

Martin