'12 A4 TFSI revving on idle

Clonliffe Resident

Would appreciate any help on this. My A4 started revving on idle up to about 2000rpm then dropping back down again. The problem didn't seem to bad so the car was driven for a few days but then an engine warning light came on so took it to dealer. To diagnose problem without fix was going to cost over €300! I said I'd seek a second opinion. There computer diagnosed a fault p050700 idle control system rp. Interestingly the problem is far less noticeable with the air conditioning on. Any suggestions that doesn't lead to an endless money pit? Thanks.

Tea drinker

It may be something that an independent could work on better than a main dealer. I think asking 300 upfront is a bit steep, but to be fair there could be a bit of checking involved in the engine, a generic google of the fault shows:

A vacuum leak Leaking air intake after the throttle body EGR valve leaking vacuum
A faulty positive crankcase ventilation (PCV) valve Damaged/failed/dirty throttle body
Failed EVAP system
Failed IAC (idle air controller) or faulty IAC circuit

Read more at: https://www.obd-codes.com/p0507
Copyright OBD-Codes.com

The failed PCV valve or leaking hose would be cheapish fixes any independent could do, and any independent specialist would know better where the fault is than my guess (my guess is PCV valve failed)
There's a few guys on this forum work on VAG cars e.g. George Dalton.

Clonliffe Resident

Many thanks for this Tea Drinker. I took it for a second opinion and the mechanic identified (within 4 seconds of popping the hood) a faulty "Breather Valve". Would this be the same as a PCV valve? He said that the diaphragm had gone on mine and that it was a common problem. He could order the part and have it installed in an hour. Am still shuddering at the service from Audi though.

Tea drinker

Clonliffe Resident wrote: »

Many thanks for this Tea Drinker. I took it for a second opinion and the mechanic identified (within 4 seconds of popping the hood) a faulty "Breather Valve". Would this be the same as a PCV valve? He said that the diaphragm had gone on mine and that it was a common problem. He could order the part and have it installed in an hour. Am still shuddering at the service from Audi though.

Yeah it's the same thing, good result in the end anyway. Main dealers in their glass palaces.... far removed from reality sometimes

Toyotafanboi

Tea drinker wrote: »

Yeah it's the same thing, good result in the end anyway. Main dealers in their glass palaces.... far removed from reality sometimes

I think the independent has himself undervalued. If he's talented enough to nail the fault inmediately, what's the use in all that talent to go out and work for nothing.

dodzy

Toyotafanboi wrote: »

I think the independent has himself undervalued. If he's talented enough to nail the fault inmediately, what's the use in all that talent to go out and work for nothing.

Price wasn’t mentioned. I’m sure the Indy got paid what he felt was a fair price for the supply & fit. Good result OP. Had very similar problem with older A4 Quattro. Systematically crimping vacuum pipes one by one got to the issue. Faulty ‘puck’ aka PCV valve that cost the price of a few beers to replace.