Knock Sensors

[Marconi]

     I have a 2006 Silverado 5.3.   I have been chasing lean codes on bank 1 and 2 for months.  Cleaned MAF, Throttle body etc... Chased it down to a leaking air intake manifold gasket.  Finally got around to pulling the manifold and replacing the gasket.  No good deed goes unpunished.  Since I had the manifold off I decided to replace the knock sensors just for good measure "while I was there".  No longer getting lean codes but both of my brand new knock sensors are throwing low voltage codes.  The fact that both are throwing codes should be a clue.

     Any advice on where to start?  I really don't want to pull the manifold again if I can avoid it.  I put in new plugs and wires too.  The truck runs great despite the sensor codes and check engine light.  Anyone else have this problem?  Any feedback would be greatly appreciated.

    

[CamGTP]

Did you replace the knock sensor harness?

 

If not, that's likely the reason for the codes. The wiring in that harness just gets completely baked over the years and moving the wires around can break them internally and cause weird voltage codes.

[rjgti]

what he said^^^^^^^^^^^^

[Mr. Z71]

Here’s the story on my ’03 Sierra with a 5.3… Had an intake leak so the shop recommended replacing both knock sensors and harness while they had the intake off. Done. 1,236 miles later, threw a knock sensor code (think it was low voltage). The shop replaced both sensors under warranty. 204 miles later, threw sensor code again. Shop replaced both sensors again under warranty. 31,558 miles later, still no codes.

The problem… sensor brand. The first two sets that were installed, and failed, were BWD #S8696. The last set installed and still going… GM #12589867. Moral to the story in my case… stick with GM. Not saying this is your problem, but it happened to me.

 

What brand did you install? I'm curious.

 

[davester]

Yeah, these trucks like ACDelco sensors.  It's also possible to just get bad parts, and in particular, knock sensors can be damaged just by dropping them, even in their box...

[Marconi]

Used AC Delco.  I'll replace the harness and see if that clears it up.

 

Thanks