2.0 TSI high idle on start, rough idle after, engine light

[jtbrown]

Today my engine has started to idle badly. When driving it feels fine, but my engine warning light has come on and is staying on.

When I first start the engine it idles at about 1500 rpm for about 0.5 seconds and then drops back to about 800 rpm. Each time I slow down and stop the engine jumps to about 1200 rpm and then dies down back to about 800 rpm again. It's only started doing this today. I've just filled my tank with fuel hoping that it was a fuel issue, but it's still happening. There's also a high pitch whining noise coming from somewhere in the engine bay but i'm not sure where.


Here's a video:
https://www.youtube.com/watch?v=9LqoCHsAhuE

[Cuprabob]

First thing to do is have it scanned with VCDS to see what fault codes are stored.

[jtbrown]

I've just scanned it with my dads OBD tool. Got a fault code P0171 and it basically says it's running too lean. Could it be something like an air leak or a faulty sensor?

[Cuprabob]

My guess would be either an air leak, faulty lambda probe or a faulty MAF.

[jtbrown]

My girlfriends dad managed to figure it out by spraying brake cleaner around the engine, it picked up when sprayed near the top of the engine. Basically the diaphragm had corroded (had some holes) in the PCV valve on the top of the engine. I've just replaced the part today, was pretty easy just a matter of unbolting it and bolting the new one on!

Can buy a non OEM replacement diagrams on ebay for £20+ but they had mixed reviews... to get the OEM part the whole unit needs replacing which cost approx £70 from a VW dealer.

Part No: 06H103495E

[mjgreaney]

Thanks for this. Just had the same problem and have resolved it.