Engine management gremlins!

[K2]

The engine management light on the dash keeps coming on, staying on for a few days and then going off!
Over the last couple of months I have worked out that it comes following driving in wet conditions, and goes off after a few days of dry weather. How strange is that?
I don't have a diagnostic kit so i cant look fo fault codes in the system which i think should be stored in its memory in any case, for when it is acessed.
Wierd though. I have been trying to figure out what it could be:
faulty maf unit, but how would this be effected by wet weather,
faulty sensors, faulty injectors???
Any ideas?

[Golich]

If you are planning on keeping the car. Its well worth buying the diagnostic tool VAGCOM for issues just like this its the best £150 or so you can spend!

Don't be tempted to buy the cheap copy leads from ebay which at best are intermitent and at worst don't work. Get the real deal from RossTech and you'll get a wealth of support usually within the hour when you register with their yahoo forum.

[DavidT]

I agree with Golich, get VAG-COM, well worth the money, even if you're not into the technical side of car ownership.

If you turn up at Donington on Saturday, I'll scan it for ya -

[K2]

Golich, thanks. I am planning on keeping the car.
Will look into the software, and interface.

[K2]

cheers dave, seems like it pays to get get a vag-com, so i will put an order in and enter the mysterious world of fault code analysis

[jon@work]

I had a fault recently that only happened with a bit of rain, but my car would go into limp mode. Diagnostics at John Fox showed that the fault was the throttle pedal potentiometer, so that was changed (£130), only for the fault to reoccur 2 months later. When I pointed out to them that the fault had only happened since the wiper linkage was changed, they investigated further. Turned out that when the front wiper linkage was changed, the plastic ECU box/container was damaged and as a result leaked, and the ECU was sitting in water.

[neckarsulm]

jon - thats a great example of how a diagnostic tool is only as clever as the operator!
many fault codes could quite easily relate to wiring issues rather than the component itself, while numerous items wont log faults if faulty e.g MAF.
I wholeheartedly recommend original VAG COM leads, had mine for years and no problem, been through 3 laptops though!