Knock Sensor Trouble Code

Within starting my car, the knock sensor code comes up within 4 seconds, all the time.

I went under the car, tested the wiring and the sensor, and all is fine.

(my own PCM is no more.. gave it away, so im all stock right now, besides my knock module hack, which this trouble code appears even with the correct L99 module too)

Try a new knock sensor.

If replacing the knock sensor doesn't work, check connections at the sensor, at the PCM and everywhere inbetween.

The knock sensors were already new, they were replaced before I got the car couple years ago (and it's always complained about the knock sensors)..

The connector and wiring is fine. I used a continuity test between knock sensor and the connector on the PCM's harness, it's fine, along with knock sensors ground.

In that case, try a new (or your old) ESC module.

In that case, try a new (or your old) ESC module.
As mentioned in my original post, I already did try putting the L99 module back in, to no avail.

As mentioned in my original post, I already did try putting the L99 module back in, to no avail.


as i am sure you know the knock sensors produce an a/c voltage that varies in amplitude as engine noise increases. if you have an exhaust leak this can throw a knock dtc . quick test ignition on engine off disconnect knock sensor connector , from connector to ground 5volts dc . with engine off measure resistance of knock sensor should be 90k-107k ohms. with engine off set meter to low voltage a/c volts measure at knock sensor to ground then tap on engine any voltage? repeat all on other side anything different? usually the connections to sensor fail! also these devices are fragile if dropped n/g..............if all checks out you have bad pcm or connectors /grounds etc.........i did say meter no test lights or other caveman devices...........

You can also install a dummy resistor in place of the KS. 1994-95 KS can be replaced with a 3.9K ohm resistor, and the 1996 KS can be replaced with a 100K ohm resistor. If the sensor code repeats after that, it's nearly certain that the wiring is in question or the PCM is faulty.

If you installed the LT4 KS, the bias is wrong, since the LT4 KS was a 1996 (100K) and may cause trouble immediately. (Just like I told you it would a long time ago in a different Impala forum).

I have the L99 knock sensor, but the LT4 knock module, as I read would improve performance, which it did a bit actually..

Being the module replacement did improve the performance, that would lead me to think it is getting a signal from the knock sensor, because it's not retarding the timing as much..

I think I'm going to blame the PCM.

My misunderstanding. I thought you were trying to run LT4 KS on the older PCM.

If you have a scanner, you can read knock counts, or try to "fool" the PCM with the resistors just to test it.

My misunderstanding. I thought you were trying to run LT4 KS on the older PCM.

If you have a scanner, you can read knock counts, or try to "fool" the PCM with the resistors just to test it.
My scanner won't show the knock counts, just the trouble code numbers and meaning, that's it..

I will try the resistor trick sometime when i get back from my trip, i got to travel like 300 miles this weekend.