Code 52

[theking11863]

So over the last few months I've been rebuilding my 3.0 and got the thing fired up a few days ago. Thing ran fine with no codes. Yesterday I was working on it and decided to redo the mechanical timing on it because I felt like the thing might've been off a tooth or so. When I was done I felt like the timing marks were lined up a lot better than when I did it the first time, but now the thing throws a knock sensor code when I rev it up.

Could a change in the timing cause this or is there potentially something wrong with my knock sensor? Any info would be great since I don't know much about knock sensors. Side note; I have not done the ignition timing yet and am pretty sure its off a little.


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[wallytoo]

no, changing the timing doesn't throw a code for the knock sensor. in fact, the KS doesn't throw a code, either. it merely listens for predetonation, and retards the timing accordingly. a code 52 does not get thrown because of knocking; it gets thrown because there is a fault in the system.

again, to be clear, predetonation (knock) will NOT throw a code 52. the code is thrown because the ECU detects a fault in the knock circuit.

edit: also, the KS rarely fails. it is usually the wiring to the KS.

 

[kc15842]

With 52 the timing will be retarded by the ecu to protect the engine and in turn you wont be happy with the performance. Mine runs fair but when you want power the engine stumbles.
I have been fighting this now for more than a week. Did you replace the intermediate harness between the knock sensor and the engine harness?

 

[theking11863]

So if the knock sensor retards the timing, and code 52 retards the timing, I'm not really understanding how one doesn't trigger the other? Sorry if I'm being dense, its been a long day lol

I did replace the wire between the sensor and the wiring harness. That's what's got me confused, the thing was fine before the day before and then the CEL popped up. The thing hasn't moved out of my driveway or been running for long so its not like a wire could've gotten the insulation rubbed off


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[mholme]

The sensor is "listening" for detonation. If it detects it, it will retard timing, without a CEL, to prevent engine damage. If the ECU doesn't receive a signal from the knock sensor circuit in its specified range, because of a faulty sensor or wiring, it will retard the timing as a fail safe and signal a trouble code 52.

 

[64manx]

I had the timing slightly advanced and on a hot day I had a lot of pinging. I got code 52. Cleared the code set the timing back to factory and never got code 52 again.

 

[wallytoo]

So if the knock sensor retards the timing, and code 52 retards the timing, I'm not really understanding how one doesn't trigger the other? Sorry if I'm being dense, its been a long day lol

I did replace the wire between the sensor and the wiring harness. That's what's got me confused, the thing was fine before the day before and then the CEL popped up. The thing hasn't moved out of my driveway or been running for long so its not like a wire could've gotten the insulation rubbed off


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read this thread carefully, and pay attention to "shaeff".
https://www.yotatech.com/f116/code-52-tech-thread-216933/

 

[_ExpeditionMan]

So if the knock sensor retards the timing, and code 52 retards the timing, I'm not really understanding how one doesn't trigger the other? Sorry if I'm being dense, its been a long day lol

I did replace the wire between the sensor and the wiring harness. That's what's got me confused, the thing was fine before the day before and then the CEL popped up. The thing hasn't moved out of my driveway or been running for long so its not like a wire could've gotten the insulation rubbed off


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You should also check out the following thread. I went through this a few months ago and replaced the sensor and the pigtail. If you are familiar with basic coding logic it functions something like this:

If (ECM receives signal from knock sensor) Then
(
If (Knock sensor detects knocking) Then
(
Retard timing to prevent knock
)
*Otherwise proceed as normal
)
Else
(
Retard timing to prevent knock
*This functions as a safe guard in the event of knock. defaults engine
*to "safe" state
)
End

http://www.toyota-4runner.org/classic-t4rs/229349-quick-code-52-question.html#post2561689

 

[kc15842]

Did you buy a Toyota Knock Sensor?