Nissan Repair: 98 Pathfinder KNOCK sensor, 30s 40s, noticeable problems

Question
Awhile back, during a yearly auto inspection, as required in PA, I was notified that the SERVICE ENGINE light was on and the code specified the KNOCK SENSOR. I have been driving the car now for about 2 years with the SERVICE ENGINE light on, with no noticeable problems because I've been told that it would be a minimum of $800 to replace the sensor and I just can't bring myself to part with the $$$.

Anyway, when we have a stretch of very cold weather (in the low 30s - 20s)the SERVICE ENGINE light goes off. It stays off for as long as it's cold, and comes back on as soon as the temperature goes back up in to the high 30s - 40s. I was wondering why this happens, and also if this may be any indication that the SERVICE ENGINE light is incorrect?


Answer
Mike,

The knock sensor is defective and it stops giving you the problem in extreme cold since the engine really has to work hard to knock.  The knock is caused by a hot engine and pre-ignition.  I would replace the sensor and be done with it.  The code is correct.  But, it is a pain to change since the intake has to come off to get to it...