1989 3vze...I got the dreaded code 52 and it seems it can be 4 things. 1) knock sensor itself 2) sensor wire harness 3) wire from ecu to the sensor harness 4) the ECU can be bad.
For those of you that had this code and fixed it, what was the problem??

 

I replaced the pigtail, the sensor, and then ran a new shielded wire back to the ECU. Hasn't given me any problems since.

 

Mine was the sensor/pigtail harness. I checked continuity to the ecu and resistance first. I then bought a new sensor and harness and drilled/tapped the engine lift hook on the drivers side rear head. Code went away so I had the mechanic move it to the correct location.

 

During the engine rebuild I cleaned the threads in the block for the original sensor and reinstalled. I replaced the pig tail with a OE replacement ( less than $20). I made a new shielded cable connected between the pig tail and the ECU and its been perfect.

 

If you have code 52 you already know its not getting to the ECU. Which means no matter what you need to get access to the pigtail. Once the pig tail is in hand you can test the sensors AC voltage output. If you have output it's the harness side wire. If you don't have output you move along to the sensor pigtail junction.

Best bet is to assume it all needs replaced and have the "kit" on hand.

 

After a good battle what cleared my code 52 was acquired different shielded wire from junkyard that had good cont. In both the signal and shield wires then soldered it in just before the ECM and sensor. Fixed it with no other issues. Man was it nice to see that check engine light go off lol