Two times this month I was driving my 2006 Audi A3 on hot days, sometimes at fast speeds (we’re in Montana where people drive fast on the highways, and there are hot temps this summer – often at high elevations), and was experiencing some kind of engine jerkiness.

Basically, it felt light the power dipped – almost as if the car downshifted – and then it returned back to the same speed.

The first time this happened, I had to sometimes hit 3,000 RPM for the car to return to its original speed, and the engine light went on -- it was a solid light, not flashing. The mechanic who read the codes said that they were: 12555; 12403; 08851 – and said that the first two codes relate to fuel pump and fuel pressures.

I took it to my mechanic, who’s well-regarded and experienced with Audis, but he couldn’t duplicate the behavior and wasn’t able to find a problem.

The second time this happened, the power dips happened more frequently but the engine light didn’t go on. The power dips – and then return to full power – occurred on a highway (again, with hot weather, occasional fast speeds, and high elevation) and it seemed to happen with the was less than a full tank of gas. When I filled the tank, it felt like the power dips stopped for a little while – until I burned off more fuel. But this might not be the source of the problem.

Once again, I took it to I took it to my mechanic, but he still couldn’t duplicate this behavior and wasn’t able to find a problem.

Does anyone have any ideas what might be causing this problem??

Thanks!!!