After getting all kinds of weird error codes on my polo and an annoying blowing fuse I finally managed to track down the cause of the fault. Oddly the two components that the error codes pointed to were not at fault.

The culprit turns out to be a little heater on the breather pipe from the crankcase up to the airbox.

Is a small thing, only fed from a 5A fuse so not sure how much heating it will actually be able to do.

It is almost a total short to earth so is knackered...


Anyone know what its purpose is? Should I pay VW the asking price and fit a new one or just electronically disconnect the faulty one and leave it be!?


The heater was blocked up with mineral deposits and a bit of maiyonaisy gunky.... I also seem to be getting a bit of oil inside the airbox..... presumably from the breather. (don't seem to burn a noticeable amount of oil over 5000 miles)

Seems a daft feature given that it is sat right next to to a giant, red hot piece of metal (IE the engine)

Any thoughts from the knowledgeable folk here?

[Edited on 15/12/12 by tegwin]

Put a 40 ohm resistor in the circuit and see if it clears the codes.

VW these days seems to have a fixation with making systems as complex as possible.

Error codes only tell you the effect of a faulty component not the cause For example I've recently had a Ford Ranger with the code PO 093 which comes up as "fuel leak detected-- major leak " possible cause fuel leak, fuel pressure sensor/wiring fault. No leak was found, pressure sensor and wiring checked out OK but changing the fuel filter seems to have rectified the fault . Look for the cause of the problem , not the effect. Cleaning the breather and throttle body may help . Suspect the heater may be to help crankcase fumes to be burnt off easily?

Fault is definitely the breather heater.

Have made it electrically safe and re-assembled the car. No more blown fuses...

Will see how much VW want for a new one..... rather tempted to just leave it as is now though.


To be fair the two apparently un-related fault codes did lead us to the actual issue as it helped pintpoint the part of the loom/system that was at fault.