What does this symbol mean?

[Rita]

following on from my earlier thread, my 1.2 Mk2 fabia has an intermittent fault, when warmed up it feels as if it is missing on one cylinder, and if i put my foot down it picks up suddenly.  Previously i had no warning lights, however this morning, after changing the engine oil and filter, spark plugs, and probably most relevantly, the air filter, after about 5 miles the fault recurred, and I  got the following;

 

 

My understanding is that this is an engine emissions warning, which implies the engine management is sensing a fault in combustion?  if this is the case, then what order should i start looking at things?  are there any sensors i  should look at first?  Also, the fact that the car feels like it is missing on a cylinder, would a failing coil give this warning ( incomplete combustion being picked up by a sensor?)  Any help / suggestions would be welcome.

[Breezy_Pete]

Yep, coil failure will give you that.

[Ootohere]

First i would have the spark plugs out and recheck the Gap.

 

What were they pre set at, and were all checked before fitting.  (Is it a 3 cylinder or 4 cylinder 1.2?)

Did the car run OK before servicing?

I hope the Ignition Coils were not damaged when changing the Spark Plugs. & are now back on correctly.

 

As to the Air Filter, one might assume you have that in right, the Air Box sealed and no wire or breather pipes not on properly.

 

EDIT.

So you already had an issue. 

 So if the plugs were done right you know that you can suspect the coil, especially after the Gap on the plugs removed.

http://briskoda.net/forums/topic/443548-12-htp-2008-rough-running-dodgy-coil 

Edited 23 January, 2018 by AwaoffSki

[Rita]

AwaoffSki,  yes plugs are fine - gaps checked at 0.9mm when fitted, correctly installed. 3 cylinder engine. Car had the same physical symptoms before servicing, but no emissions symbol.  Air filter was filthy, so new filter fitted correctly.  Ignition coils, due care taken in removing and replacing.  only other thing is that the brake servo vacuum pipe had split either side of the NRV, so temporary repair with self amalgamating tape and jubilee clips, joins are now sound and not leaking.

 

Interestingly the emission symbol hadn't  come on prior to servicing, and when it did it was after having driven about 5 miles, up until which time the car was running well,   the only significant changes being the repaired vacuum pipe and the new air filter ( the old spark plugs weren't that bad, but i decided to change as i didn't know how old they were).  All plugs have a healthy light brown colour, no oil fouling etc. 

[Ootohere]

They were at twice the gap you said before, and car running rough.

Best check that breather again.

It is the Exhaust emissions control light. different from the EPC, but can come from a Misfire, or was the car sitting ticking over much before driving after the servicing.

Can you read the fault codes, can you reset the light?

[Rita]

Tick over has always been ok. I've got a piece of kit which is meant to read the codes, so I'll plug it in this evening and see what it says. 

[Rita]

So,  accessed the engine codes last night,   and got the following:

 

16556-039 Fuel trim:  System too rich:  Bank 1:  P0172

17549-167 Load calculation cross check Implausible value P1141

16518-232 Oxygen ( Lambda) sensor B1: No activity: P0134

16516-038 Oxygen (Lambda) sensor B1 S1: signal too high: P0132

 

Readiness test:

 

EGR sys         FAIL

Heated O2   Pass

O2 sensors  Pass

A/C                Pass

Sel air inject Pass

Evap sys       Fail

Catalyst        Pass

Catalyst conv  Pass

 

i'm still checking on the internet to find interpretations for the above, but would appreciate any suggestions from the forum.  Based on the above  i'm tending to think what i'm experiencing is not a cylinder missing due to a failed coil, but more likely an over rich mixture 'choking' the engine, either a sticking throttle valve, or a lambda sensor giving a wrong reading to the ECU which is making the mixture too rich?   

 

 

[Rita]

Having looked further into this, there is a suggestion that this could be a rogue MAP sensor or possibly malfunctioning throttle valve?  Does anyone agree?  my first port of call will be to give the intake a dose of Wynn carburetor cleaner, and take the MAP sensor our for a clean.

[Ju1ian1001]

Lambda/oxygen sensor is at fault , disregard the readiness test's as these are just telling you the sensors are switching on, the may not work or act as they should.

 

It's the 2 bottom codes in the top colum the gives the much needed info, the top 2 codes will happen as the sensor won't work proparly so the the cars ECU will work with basic settings so the car run runs.

 

Change lambda sensor and clear the codes and see what happens, duff lambda sensors can and do cause missfire's.

[Rita]

Julian, many thanks.  As both codes refer to ' sensor B1 S1' i assume the fault relates to the lambda sensor prior to the catalytic sensor ( i believe there is also one after the cat, but i haven't got my Haynes to hand to check). 

[Ju1ian1001]

Yes thats right S1 is the first sensor. On your engine you will only get B1 as there is only one bank of cylinders, S1 is the pre cat sensor, S2 would be the post cat sensor. Bot sensors work together and fine tune the fueling of the engine.

 

I would also can the MAP sensor out as well, always a good thing to do as they do get pretty gummed up.

[Rita]

Hi, help please.  I picked up a replacement sensor today from europarts- lambda sensor head, threads, no of wires and wire colours the same, but plug is a different size.  Do I return and try and find one with the correct plug, or treat it as a 'universal' and cut the plug off and join to the old plug?

[Breezy_Pete]

Take it back. ECP seem to specialise in supplying incorrect parts. 

[Arghhhhhelp]

I'd have a pressure test done as to rule out possible head gasket (early signs of) fail.

Old car I once had ran rich

Had similar codes but no sign of head problem till pressure test was done..

Not saying yours is but could be maybe worth a shot

[Rita]

Ok Wino, that's what I thought I should do, just wanted to get this sorted, so trip  into Bath for me tomorrow. Looking at the pictures on the eurocarparts website the Denso sensor  is the right one, should have gone for that one in the first place.

[Breezy_Pete]

What year and engine code is your car? If you go to 7zap.com, choose Skoda, then Fabia, then year, then electrics section. Inside there search for a section with lambda in the title, then look through all the item 12s trying to match your engine code and year, for lambda sensors before the cat. I would do it for you but I'm on my phone for the time being. If you can get the VAG part number it should help you to get the right part.

[Rita]

Thanks, I've got the original sensor out, part number is 03E 906 262B, which equates to Denso DOX-0121 or DOX-1707, so I'll check against the one I collect tomorrow ( unfortunately the europarts website doesn't recognise the skoda part number). 

[Rita]

So, update, I've sourced a Denso lambda sensor from eurocarparts - the Denso one they supply is DOX-1707, and has the correct plug etc.  When taking taking the old sensor out ( 22mm spanner) it was tight and I had to ease it out ( half turn out, quarter back, half out etc.) and when i got it out, the bottom two threads were burnt, hence why it was tight.  New sensor comes with copper grease, so anyone reinstalling a used sensor should use copper grease sparingly on the threads.

 

All fitted, OBD codes reset, and so far so good, so this appears to have sorted the problem.  Thanks for all the help.

[rum4mo]

T think that Lambda probes used to come with the thread coated with a grey high temperature grease that was loaded with tiny glass spheres to stop it seizing up with age, I don't know what the cat will think about copper grease.

[Rita]

The first one I got had the grey grease, but the Denso one came with a sachet of what looks like copper grease, but I must admit I haven't looked at it closely.  However you only put a very light smear on the threads, so it shouldn't get anywhere near the cat. 

[rum4mo]

Maybe it is okay to use that grease then, I seem to remember finding some spark plug anti seize paste once, and it was a bit like copper grease - so it was being used in the same sort of location. Strange to me that the wrong one came with the colour of anti seize paste that I would have expected as I've fitted a genuine VW Group sourced one once.

[Rita]

Just to finish this thread,  a week later and all is ok, so it would appear to have been the lambda sensor as identified by the OBD codes. Just glad i had the kit to read and reset the codes ( bought originally so that i could reset the service code on my Octavia) , not sure how anyone without an OBD reader could have identified this fault. 

 

Thanks for all the help and advice.

 

Now, back to simpler things and my '68 Morris Minor - no computer or OBD codes, but an awful lot more rust!!!!