What does code P0325 mean on a GMC and is it safe to drive?
P0325: Knock Sensor 1 Circuit Malfunction (Bank 1). Here's what it means on your GMC, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
The PCM isn't receiving a valid signal from knock sensor 1. Without knock feedback, the PCM retards ignition timing as a safety measure, reducing power and economy.
Common causes for your GMC
- Failed knock sensor
- Corroded or broken wiring/connector at the sensor
- Actual engine knock from carbon buildup or low-octane fuel
Symptoms
- Check Engine Light
- Reduced power and fuel economy (PCM retards timing)
- Possible audible knock or ping under load
Typical fixes
- Replace knock sensor
- Repair wiring and connector
- Use correct octane fuel and address carbon buildup
Repair cost range
For a GMC, repairs for P0325 often fall between $150 and $500, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on GMC
GMC Sierra P0325 on Gen IV LS 5.3L mirrors Silverado—GM's TSB for the knock sensor harness corrosion applies to all GMT900 trucks and SUVs (Silverado, Sierra, Tahoe, Yukon, Suburban, Avalanche). The fix is replacing the harness with an updated sealed connector assembly (P/N 12110027). On Acadia 3.6L V6, the knock sensor is accessible from above; corrosion at the sensor connector is the most common cause. GMC Sierra 6.2L owners with performance tunes should verify the knock sensor is fully functional—ECU retard strategies depend on accurate knock detection.
Most commonly affected models