JW A4Q

I've been experiencing an issue for the past year or so, and need to make a decision about a potential (expensive) fix.

Every few months or so, when I'm driving my 03 A41.8TQ (manual) on the highway and get into the 120km/h - 130km/h (72mph-78mph) range, the Check Engine Light will come on. However, there are absolutely no noticeable issues with the car (performance, "feel" are status quo). After several days, the CEL turns off and everything is good until the next random highway trip.

The garage has determined that the fault code is related to the knock sensor - of course, it's the one where you have to take off the intake manifold, blah, blah, $$$$.

I don't notice any pings, hesitations, etc, and I only use premium gas.

Any thoughts/similar experiences?

Pete@ECSTuning

Next time it comes back on you should scan the car at a local autoparts store and post us the error codes. From that we can further diagnose the issue, but without them we would be kind of shooting in the dark.

JW A4Q

The error code is P0328. Knock sensor 1. Upper limit exceeded. Intermittent.

Ulf

Had the same happen a while ago. Random CEL - P0328. Went for the expensive option and had the knock sensors replaced. Then light came back intermittently. WTF?? Don't know if it's related at all, but after replacing the sensors and getting frustrated with the recurring CEL, I switched gas stations from my local Conoco to Shell. Never had the CEL since.

JW A4Q

Thanks, Ulf.

I'll try tracking gas vs. CEL timing and see if that turns up a pattern.