Is knock sensor code for properly sensing another issue or its own issue? (4 Viewers)

[BullElk]

Is a knock sensor supposed to sense an issue with engine resulting in a corresponding diagnostic code (but not the "knock sensor" code) ?

Or is a the actual "knock sensor" code ONLY designed to alert that the actual sensor or wiring is faulty?

I have the knock sensor code coming on sometimes and then not at all. When on, it may take 100 clears to finally get it off then sometimes maybe once or twice and it's cleared.

I'm thinking if the wiring was bad the code would never clear but if there is some other faint intermittent engine sputter of some sort then maybe that is why the code of off and on.

Trying to decide if replacing the actual sensor is the work to do. No other codes present.

Thanks.

 

[DuckLN]

What cel code(s) are you addressing?

 

[BullElk]

What cel code(s) are you addressing?

Now they're not on but I think they were p0325 and p0330. Just as sure as I drive away for an overlanding trip in a couple weeks the code will come back and not clear.

 

[Mighty Mouse]

Following, I have a knock sensor code 52 OBD1 on my ‘94 Cruiser that despite replacing the knock sensor with a $250 OEM sensor, and a shielded pigtail it keeps returning after I clear it. It has kept me from being able to drive it for over three months now and I stumped.

So along with the original question: When I put the Cruiser in Drive, when attempting to accelerate, the engine stumbles like it’s very lean. Since I can’t correct the Knock Sensor code, could it be that the code is thrown because the engine is lean and consequently throws the code?

MAF or Throttle Body?

 

[SteveH]

I got a knock sensor code a couple years ago ('99 LX - for one of the 2 sensors) and replaced both sensors ($156/ea - dealer), checked my wiring, replaced the starter while I was in there, removed the mouse nest, and buttoned it all up.

Never have had a code since. The first time I got the code, I cleared it, and it came back regularly, which implicated the sensor.

 

[syrinxstar]

It seems that often it's a rodent issue and you can look in the front of the engine with a flashlight just under the intake manifold and look to see if you see sticks, stuff, whatever, in that space. Mine was clean but I was getting a code for the drivers side knock sensor.

I pulled off the manifold and tried to follow the procedures to test the sensor but I don't think my home equipment was good enough -- inconclusive. I did visually check the wiring, which looked fine. I also checked for continuity from the sensor connector to where the wire inserts into the ECU in the glove box while shaking the wire harness for both wires. That was all fine so I concluded it was the knock sensor and replaced it. Problem fixed -- that was 8-months ago.

All this is to say that it's either the wiring or the sensor that's likely giving you the code.

While in there I also replaced the starter, the other knock sensor, and replaced the fuel injectors. That last one really changed the performance of the engine. 240k miles on a 2004 and the old injectors must have had some clogging. It runs so much better -- much more responsive. Didn't drive it off the lot but I think I'm closer to what it was like new.

 

[BullElk]

That was all fine so I concluded it was the knock sensor and replaced it. Problem fixed

That seems to be the solution for most folks I have seen, including mine years ago. I am just curious what the designed function is of the knock sensor and what happens to know if it IS working properly. ?

 

[SteveH]

Traditionally, the knock sensor is a microphone (of sorts) that listens for the sharp rap of pre-ignition (knock) and the engine computer then retards engine timing to prevent it. Newer sensors may be more exotic in the control method, but this is the basic principal. I think you can do a simple resistance test on a sensor, per the FSM.