Erich Fuchs

I keep having an issue in my 2013 A4 2.0T Quattro MT anytime the outside temperature is below freezing where if I'm holding the clutch in or in neutral the rpm's will surge between normal and up to around 1800 some of the time. It seems to just bounce up and down to different amounts the entire time I'm sitting there until I start driving again. I've also noticed that if I turn on the parking brake the idle drops down almost immediately to normal and stays there without any surging. After enough days of this happening it will trigger the check engine light to come on with the codes P2279 and P2187. I replaced the PCV valve a couple weeks back when it started happening but didn't replace the hose from it to the intake manifold. Any ideas what could be causing this? I may replace the hose from the PCV to intake tonight just to rule it out but I'm not sure if that's the problem due to the issue seeming to go away with the parking brake on.

treilley

This engine/tranny combo will surge by design when letting out the clutch. Supposed to aid in stop and go traffic. Sounds like something is malfunctioning with that system. I am not sure but it may be vacuum driven. Check the hoses.

Erich Fuchs

So I now have some additional info that may or may not help with this. I had the car at the dealer yesterday for the auxiliary coolant pump recall to be done on it. When I drove the car to the dealer the idle problem was happening the entire way which was about a 45 minute drive. However when I picked the car up last night it ran perfect the entire drive home and again ran perfect this morning driving to work with the outside temperature being the same as yesterday morning. I wonder if part of that recall is a software update that may have corrected the system you mentioned?? I'm going to plan on checking the hoses over this weekend anyways to see if any are leaking or need replaced but currently at least the car is running fine. I also had the dealer do an oil change while they had the car since it was almost due for one and currently too cold outside for me to want to do it myself but I wouldn't think the oil change would have anything to do with this problem.