Hi my car is having problems which I have traced back to fluid in the top ECU connector. When the fluid is present the engine reports various faults related to camshaft position (p0341&2), various ECU faults (p0606 p0642 iirc), misfiring on cylinder 2 (p0302) and p1250 (fuel mix). When removed all the faults go away.

 

The liquid feels greasy between the fingers rather than wet, so I am thinking it might be engine oil that is wicking up through the loom, possibly from the camshaft sensor.

 

I wondered if anyone has experienced add resolved this problem. A pin diagram or table for the connectors might help me locate the fault too.

Can help with connector pinout in a while. What year is yours? Can't say I have heard of this fault before, any sign of oiliness in the cam sensor connector?

 

Water seems more likely, draining down the loom out of the scuttle area.

Cam sensor uses pin numbers 96, 105

Knock sensor on 101, 102, 109

MAP/intake temp sensor uses 93 and 95

Crank speed sensor 89, 99, 106

Coolant temp 83, 104

Injectors 1-88, 2-87, 3-85

Throttle Body  90, 91, 92, 97, 119 and 121

EGR 84, 108, 115

Coilpacks 1- 112, 2-113, 3-100

I think that's most of the ones on that conn?

My prime suspect is pin 106, followed by 98 and 99, and possibly 82 83 84. More fluid today than yesterday. Definitely in that lower end of the connector. Could be migrating within the connector I think from the source. 

 

I think it's not petrol, oil or washer fluid, therefore coolant, power steering or brake fluid. Thanks very much for the pins.

Edited 15 June, 20188 yr by alexnharvey

Is it possible to dry it out with say, an electrical contact clean and then fit a latex glove over it, tie wired at the cable end? Or something of this ilk!

 

Edited 15 June, 20188 yr by mrgf

How would that help?

 

 

 

Edited 15 June, 20188 yr by alexnharvey

Try to get a sample of the fluid onto a clean white rag/tissue.  Coolant should be the only pinkish one, I think, and my favourite candidate.  See if there's fluid inside the connector of the coolant temperature sensor. 

9 minutes ago, Wino said:

Try to get a sample of the fluid onto a clean white rag/tissue.  Coolant should be the only pinkish one, I think, and my favourite candidate.  See if there's fluid inside the connector of the coolant temperature sensor. 

 

Bingo, coolant is dripping out of it. Just replace the sensor to resolve?

I expect so, yes.  Was it still giving sensible readings?

Yes, reading fine. Had been losing a small amount of coolant over time. Replaced it with a cheap one a couple of years ago when it stopped reading properly. I can maybe just do the o-ring.

I think if it were just the o-ring leaking it would be an external leak only, not up the connection? Not sure, please let us know what fixes it though, very strange one!

 

 

The discolouration on the brass showed coolant had been passing the o-ring. The o-ring may well be 13-14 years old! Then maybe pooling in the housing and being wicked between brass and plastic housing into the wiring area and through to the pins. That's my hypothesis anyway. Refitted it with some plumbers tape and silicone grease to test this theory. However I'm curious about how the sensor continued to give good signal.

 

I'm thinking of buying a Febi bilstein sensor and o-ring from Amazon or eBay rather than straight from VAG. 

Edited 16 June, 20188 yr by alexnharvey

Good value genuine sensor here: https://www.ebay.co.uk/itm/GENUINE-COOLANT-TEMPERATURE-SENSOR-06A-919-501A-AUDI-SEAT-SKODA-VW/172498391120?epid=1748924250&hash=item2829b49050:g:4rcAAOSwWDBbAT0U

 

I'd be interested in doing a full cut-down/post-mortem on the old one if you don't fancy doing so yourself?

 

 

Yes, if I don't have time I'll pop it in the post.

 

Do you think there's any benefit in trying to flush the coolant from the wire with distilled water or isopropyl alcohol?

 

Thanks for all the help. 

3 minutes ago, alexnharvey said:

Do you think there's any benefit in trying to flush the coolant from the wire with distilled water or isopropyl alcohol?

Good question. I think I'd play a watching game and if anything odd happens with temperature readings in the future, cut and splice a pair of new wires in from close to each end, or including a new connector at the sensor end. 

Once the source of fluid is curtailed, I'd think it will very gradually dry out with engine bay heat, hopefully the anti-corrosion additives in the coolant will help prevent destruction of the copper wire.