1990 toyota 4runner code 52 knock sensor

Asked by Jan 31, 2017 at 07:59 PM about the 1990 Toyota 4Runner 4 Dr SR5 V6 4WD SUV

Question type: Maintenance & Repair

Code 52 knock sensor boggy feeling mechanic
said it sounds like my motor is running off of 5
cylinders i ordered a new knock sensor. Any one
who can shed light on this will be appreciated.

1 Answer


The knock sensor is like a microphone that listens for spark/knock. When it hears pinging or knocking it sends a signal to the computer (ECM). The ECM then electronically retards the ignition timing to stop the pinging or knocking. If the knock sensor is malfunctioning it could be making the ECM severely retard the ignition timing. This will cause loss of power, the engine will run hot and possibly boil over when you shut it off. It can also cause late transmission shifting if it's an automatic with a vacuum modular. One other thing to be aware of on this subject is if your engine has developed a valve tap the knock sensor may hear it and severely retard the ignition timing unnecessarily. This happened to me on my '93 Chevy Caprice when it was near the end of it's life. I had to disconnect the knock sensor wire at the knock sensor module for it to run right those last few months I had it. HTH. -Jim

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