Bucking, stuttering, loss of power = bad motor mounts

[Jeff V.]

A couple weeks ago I was coming home from work, and my car started idling a little funny at traffic lights. I tried not to think too much of it, but as I continued home, it got worse, Eventually the engine started losing power above 3000 rpm and running like absolute crap. This was all over the span of 15-20 minutes. I was down near the bottom of a tank of gas, so I was really hoping it was just bad fuel. So I topped it up, and drove it for about another mile. Still no good. I got home, hooked up my HexNet, and found this code.

005489 - Left engine mount solenoid valve (N144)
P1571 - 001 - Short to plus

I thought that was more of a symptom than the cause, but it turns out I was wrong.

I had the car towed to CarMax, who in turn sent it off to the local Audi dealer. The dealer said both motor mounts were leaking hydraulic fluid, and one of them had caused an electrical short which in turn caused the ECM to freak out and the car to run like crap.

This sounded really fishy to me, but some Google searches turned up other instances of this with other Audi owners. There were several cases with cars that had electrohydraulic engine mounts. Not just B8s. This is an ad for upgraded solid mounts, but so far it's the best picture I've seen that shows what the stock ones look like inside. I'm trying to find some kind of factory literature that explains how they work. From what I understand, there's a valve that closes and makes the mounts stiffer (since fluid cannot compress) at higher RPM. At lower RPM, the fluid is allowed to flow between two chambers, making for a more compliant mount.



This is the dealer's description of the problem on the repair order.

Check and advice car started to sputter then would not stay running. Found fault P1571 left electro hydrolic solenoid valve. Inspected and found both motor mounts leaking causing short to ground. Replaced both mounts, completed alignment.

The replacement mount kit was 8R0-198-381-F at $429. The labor came out to $1206. Thanks to my CarMax warranty, my out of pocket was only $250.

I haven't driven it much since I got it back, but so far it seems perfect. Maybe even a little better than before. We'll see what happens as I put some more time and mileage on it. I'll update this thread if anything changes.

[Zonsolo]

Thanks for the post. Good stuff. I've thought about getting the 034 ones just for kicks.

[DreDay]

Thanks for sharing. A friend of mine has his mounts go on his S5 and it caused the car to not even run. He was getting the same fault codes. I have a leaky one I believe and looking at the 034 as replacement... Just not looking forward to the labor costs... Ugh