My 01 996TT (23000 miles) started backing off the timing and boost around 5000rpm...no check engine light. I got a code that said bank 1 knock sensor below limit value. I clear the code, car runs fine for a few days, the code and the symptom come back. I've been through several tanks of fuel of various brands with the same results...only high octane used.

I have 4 questions:
1: won't fuel quality typically create faults on both knock sensors ?
2: has anyone seen where something else caused this code (ie not the knock sensor itself) ?
3: is it typical for a knock sensor to fail at 23K?
4: has anyone changed the bank 1 knock sensor without dropping their engine? The sensor's are cheap, and normally I would just change it as part of the diagnostic plan....but...it looks like an engine out job.

Thanks for any input !

 

Knock sensor faults can be "implausible" "out of limit" or "open circuit" mine was a "out of limit" fault, indicating perhaps a faulty sensor. Once torn down (engine and trans out) I found that MICE had eaten the wires going to the sensor.

I would think you might get "open circuit" faults, but you don't. Now for preventative maintenance I'm going to change my coolant tank and fuel filter while the motor is down. Any other suggestions for preventative stuff here?