Close
QUESTIONS

RepairPal is your advocate for car care advice and guidance

Q: Check engine lite code says knock sensor fault.Tell me more
about this on 2004 GMC Sierra 1500

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
Let me know how important the knock sensors are i know they are under the intake manifold. They would be very expensive to replace. Give me some advice.
No car image 94a1663db56199c5353592009e34aaa51078a2469bed068bb8d6f0ba43accf97
Get a Repair Estimate
Guaranteed by certified locations nationwide. Learn more
RepairPal estimates are guaranteed at over 1,700 quality certified locations nationwide. Learn more
It allows the engine to run with the ignition timing as far advanced as possible. The computer will continue to advance the timing until the knock sensor detects pinging. At that point the computer retards the ignition timing just enough for the pinging to stop.

A knock sensor assures that you're getting as much power and fuel economy as is possible from your engine. As long as no unusual "knocking" or "pinging" in cylinder, the sensors will go bad at some point. You may want to replace both sensors at the same point since a bit of labor to replace.

Upgrades can be made IF you decide to fix this, check for GM TSB. Note: ALWAYS use new manifold bolts!
Or insist on having them installed! Better gaskets and a trick or two for the sensors.
Didn't find what you were looking for?