Recently, my car has been bucking on the road. I get the same feeling I get when I am about to run outta gas, but in this case I have plenty. I got the ECU codes and reset the service engine light. It's turned on twice since, and each time, the ECU code points to a bad knock sensor. Only once did I get a bad MAF sensor code.

I took it to the dealer and they said it was a bad MAF sensor, and it would cost $720.00 to fix! So I purchased a refurbished one for $267.00 and will install it myself.

I am just wondering why I kept getting the bad Knock sensor code. I'm glad the dealer said it was the MAF, because that looks much easier to replace.

Can anyone help?

 

The symptoms you describe, do sound like your MAF's variable resister has just worn though in spots. I had it happen on my BMW.
The knock sensor might be the octane of gas you are using?? What do you use. I put 87 in my car a month ago, and the light came on. I checked the code and it was the knock sensor. I put 94 (though I usually use 92) in the car and reset the ECU. I have not had the light come on since.

Good luck,
dave

 

The knock sensor malfunction by itself will not cause a MIL to light (straight from the factory manual and personal experience), it will just store the code (0325) and retard the ignition a bit. The bucking would be from the MAF sensor. The price of >$250 for a used MAF seemed high. I got one for ~$130 from a 3 year old Maxima a few years back.
BBTW, if after replacing the MAF sensor and clearing your DTC's you still get the 0325 code, replace the knock sensor. You should notice better starts and low end acceleration. Remember, the MIL won't come on for the bad knock sensor. You will need to scan the ECU in order to check for the DTC.
By the way, regarding the knock sensor replacement, my six year old son's hand was able to easily reach the bolt and position the wrench in place while I applied the force. Keep the wire attached to the sensor until it is unbolted and connect it prior to bolting in place. My mini-me made the job extremely simple.

 

if you decide to go for a new knock sensor , i have one for sale

105 shipped , new in box , bosch sensor, pic on homepage

 

A telescoping magnet pick-up tool makes it a lot easier also.

Pedro

 

Thanks for your input guys. Unfortunately, my car got so bad I had to replace the MAF sensor before any of you replied. It's good now though. Hopefully, next time I will have more time to read replies prior to spending so much money.

 

What did you pay for it? What dealer? I'm just currious... I've only bought them for a 325e... wondering on price difference.
thanks