me ecu has been giving me error code 0304 (knock sensor) for some time know but my cel hasn't been on. I have checked for continuity and there is none. Today I was driving down the road and all of a sudden my cel comes on and now i am getting 0304 and 0707(rear heated O2 sensor). Can anyone help me out with what is wrong with my car? Any help would be appreciated thanks stevo

 

If you keep getting 0304 after resetting then I think you'd be best advised trusting the CEL and getting a knew knock sensor. The first time you get an 0707 just reset and see if it comes back.

 

Get the O2 sensor first and then reset the ECU. The O2 could possibly be causing the 0304 code to be tripped.

 

I have gotten the same 2 trouble codes 3 different times now. I have just reset the ECU to see if they come back. The first time I reset the ECU, the check engine light came back on after about 700 miles. The second time the light stayed off for over 1300 miles. I am not sure if there is really a problem if the light stays off for that long of intervals. Just in case there is a problem which could be robbing me of power, I bought a new O2 sensor. I just reset my light for the third time today after I put the new O2 sensor in. I am hoping for a slight power gain from a working O2.