Knock sensor code, service engine light

Tiny
BGADDIS
  • MEMBER
  • 2000 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 250,000 MILES
Got service engine soon light. Checked code and it said knock sensor(don't know code number). Had the knock sensors replaced with OEM GM parts. Light came on after being reset each time, usually within 30 miles. Replaced wiring harness to knock sensors. Light came on again. Removed wiring harness and cleaned contacts in plug to computer. Light came back on after 70 miles. We're stumped.
Wednesday, August 12th, 2015 AT 7:07 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Given the mileage, it's more likely there's a rattling in the engine that is being detected as a knock. A sloppy timing chain is a good suspect. The clue is while driving with a scanner connected to view live data, you'll see ignition timing continually being retarded in an attempt at stopping that knock.

It's also important to know the exact fault code number. That will tell whether there's an electrical problem with the circuit, or the sensors are working properly but responding to something.
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Wednesday, August 12th, 2015 AT 10:46 PM

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