Hello everyone, this is my first post on this amazing forum which has helped me so much over the years with my wife's Mk1 2005 Fabia 1.2 HTP 12v. 

 

The above car is giving me a lot of trouble currently, (and so is the Mrs.)

 

• Car started misfiring on all cylinders when hot and go into limp mode, not going past 2k RPM.
• I replaced spark plugs and coils but the car still started misfiring when hot.
• Scanned the car and got fault codes for all cylinder misfires, as well as pretty much every other sensor in the car including both o2 sensors & MAP sensor. Also has code for low battery voltage even though its fine when tested with a multi-meter. 
• I charged the battery just in case, and replaced both o2 sensors. 

 

I am still getting the same codes after clearing. What I then realised is that at no point when getting the car to misfire when hot, had the fan kicked in.  

 

• I turned on the AC and left the car running until it got to temp and still no fan. 
• Checked the fuses near the battery - all are good. 

 

My question is, could a faulty fan be the culprit here? Could an overheating engine as a result of a faulty fan cause all cylinder misfires and throw up tons of codes? 

 

Thank you in advance for any help you can give!

 

Ryan

 

 

 

 

 

 

 

Does the temperature gauge ever go above halfway? 

Did your fuse check include blade fuses 8 and 11under the cover to the right of the strip fuses on the battery holder?

 

Hi Breezy, 

 

No - I never noticed it go above 90 but the car starts misfiring around the time you would expect it to.  I did notice burning coolant steaming from the sensor attached to the radiator. And yes - I checked all of those fuses too. 

 

Should I run 12v directly to the fan to test if its toast? 

 

Have you looked at the brake servo vacuum hose at all? They tend to crack and leak at the joints of the hard plastic sections, and the plastic will be softer when hot, so more likely to open up. I would think this is more likely the cause of your misfires than the temperature.

 

Two radiator fans or just one? 

The thermoswitch is a common source of leakage, and can generally be fixed by just tightening a little, 29mm spanner or deep socket. If you take the connector off to get a socket on, may as well bridge some pins of the loom connector whilst there to test each speed.   I'll find a helpful photo shortly showing which pins to short. Ignition needs to be switched on to check full speed, but not the low speed.

  

If it's a 6V engine it could be the dreaded burnt exhaust valves causing the misfiring.

Thanks for the pic that's really helpful - will check this in half an hour after work.  I forgot to mention that the hose was indeed split at both ends. I have replaced it with a chunky bit of silicone hose which is strong enough not to cave in and checked for vacuum leaks as best I can by ear. Still no bueno and misfiring when hot. 

*Only has 1 fan as far as I could see - I'll double check shortly.

OK so the fan works at both speeds. I have a replacement Febi thermoswitch - will replace that now. What are your thoughts?

2 hours ago, sepulchrave said:

If it's a 6V engine it could be the dreaded burnt exhaust valves causing the misfiring.

 

This ^^

Please post the actual fault codes complete. Not just your/the description of them. It will help a lot more.

 

 

ok so:

 

16687 - misfire 3

16490 - manifold/barometric sensor Implausable

16556 - Fuel trim Bank 1: system too rich

16685 - misfire 1

16684 - random misfire

16686 - misfire 2

17524 - lambda sensor heater open circuit 

01598 - Battery voltage low

 

also noticed: 

 

01314 - ECM DTC memory

 

and there are loads of other HVAC ones too but not sure they are related. 

 

 

Is one of the hvac codes G65 low pressure? If so that may explain why AC isn't triggering fan action, just not getting the high side pressure up sufficiently to trigger it.

 

I wonder if you've got some wiring damage that's affecting the positive feed to the coilpacks at high temps?

 

The oxygen sensor heater fault may point to a bust wire at the interconnect down on that bracket in front of the gearbox.

Is it an AZQ engine code or a BME?

Update: the switch i ordered was the wrong one, ordered the correct one.

 

breezey - no low pressure code, just ones regarding the circuit shorting etc. the clutch kicks in so would expect the fan to work? 

 

As a makeshift I shorted the switch so the high speed comes on straight away. Took the car for a long blast and no issues at all. Car is running perfectly and the check engine light has gone! Maybe cleared out all the poop from running lean an idling so much testing the car. 
 

I also ordered a new thermostat and sensor, when all parts are fitted i will clear codes, drive and then re-scan with another update. 
 

thank you  
 

I doubt your compressor clutch kicks in, because there isn't one. Your car has a variable displacement compressor controlled by a solenoid valve, N280. It's always pumping a little, even when A/C is switched off.

Share the hvac fault codes for more suggestions.

 

The radiator thermoswitches are not usually a failure point (other than coolant leakage), as they only carry relay coil currents, not fan motor currents, in this set-up. 

I wonder if coolant flow through radiator is low? How many miles on the clock?

See how things settle down with new thermostat etc. 🙂

Ah that's good to know - What I noticed was that the revs increased and decreased when switching the AC on/off and assumed there was a clutch. Would the revs still adjust if the refrigerant was low? HVAC Codes are: 

 

65535 - Internal control Module memory error

01596 - Motor for recirc/outside air flap no voltage

00898 - AC control circuit open or short to plus

 

I believe the engine is an AZQ (but will confirm) and I also thought that coolant flow past the fan thermoswitch could be the issue - hopefully the new thermostat will resolve that if it is. It has 95k on the clock. Could it also be the waterpump?  

The last of those codes points to an issue with the wiring to the N280 valve, I think. Reddish-brown two-way connector pair on the bracket near starter motor is typical wiring trouble area.

It's a bit odd, as you say, if it wasn't working at all you wouldn't expect the rev/load compensation. 

95k isn't particularly high mileage, so I doubt the water pump has had it. 

https://m.youtube.com/watch?v=7QTS3SD-iCA

That's great, I'll check it out whilst I'm replacing the thermoswitch when it arrives. I may just replace the water pump as I already have a new aux belt to go on as current one is fraying slightly and found a brand new FAI pump for £25 on ebay. It all looks pretty straightforward and accessible from the side.  Then the cooling system will then be renewed apart from the radiator and fan

 

 

Only thing possibly worth mentioning is that the fans can suffer a failure mode that leaves them  as 'unreliable starters'.

There are two sets of brushes orthogonal to each other, and it can happen that one pair, or one brush of a pair, gets stuck in its holder and no longer reaches the commutator.  In a how-to of fixing the low-speed resistor failure of these fans, the author unintentionally illustrates this by posting a photo of his fan's innards with two telltale, stuck back brushes, one from each pair (top two in image):

http://i4.photobucket.com/albums/y146/Imagewerx/Fan%20resistor%20fix/018_zpsdf767ee1.jpg

 

This sort of partial failure may result in "sometimes it starts, sometimes it doesn't" behaviour. 

I think a supersedence of the fan part number for the single-fan version like yours is still used in some considerably younger cars, so ebay may have some reasonably priced second-hand genuine units. I bought one a year or two back for something like £30 delivered, which seemed good value for a genuine item that was I think maybe ten years old rather than 18 or whatever.  I never installed it, as it happens, 6R0 959 455 E, I think, e.g. SEAT Ibiza 6J 2016 TSi Petrol model ENGINE COOLING FAN MOTOR and COWLING SHROUD | eBay

 

 

Legend - that's good to know!

9 hours ago, Breezy_Pete said:

orthogonal

 

Don't mind admitting that I had to google that

Ok - very defeated this evening. 
 

Replaced the thermo switch and thermostat and sensor. Plugged the fan back in and nothing. 
 

the water pump is definitely pumping as there is flow back into the reservoir.

 

I can hear that there is loads of air in the system as a result of the work and the radiator and thermo switch are not even warm when the car starts to overheat. 
 

any tips on the best was to bleed the system?? I’m starting to lose the will

 

 

Breezy - starting to think you might be right regarding the fan itself. :/

UPDATE: Bled the system so coolant is flowing once again. Same issues as before with no fans kicking in so I guess all it could be is the fan itself or the relay. Really annoyed at the time and money spent on this - have pretty much changed every other cooling part except the water pump (which I have bought but will send back). Hopefully have a fully working car for the wife soon though.