2003 Chevy Tahoe Z71 P0326 and P0332 Fault: Knock Sensor Issues After Replacement

There are no additional diagnostic trouble codes (DTCs) present, and no modifications have been made to the vehicle. • If DTCs P0327 and P0332 are set simultaneously, inspect the knock sensor (KS) harness jumper located on the left rear side of the intake manifold for loose or corroded connections. • Visually inspect the knock sensor for physical damage—drops or impact can cause false codes. • Ensure proper installation: a loose or over-torqued sensor may trigger DTCs. The sensor should not have thread sealant applied, and the mounting surface must be free of burrs, casting flash, or debris. Measure resistance from the knock sensor signal circuit (on the sensor side of the harness connector) to a solid ground using a digital multimeter (DMM). Expected range: 93–107 kΩ. With the DMM set to 400 mV AC/Hz, check for any AC voltage when the engine is off. If present, it may indicate an electrical issue or alternator diode failure. Note: A leaking alternator diode can introduce unwanted AC voltage on the knock sensor circuit, leading to false DTCs.

Thanks for the detailed response. Under stored codes: P0327, P0332, C02?? Under pending codes: P0327, P0332 All wiring and harness connections have been verified as good. Knock sensor resistance readings are 99.4 kΩ and 99.9 kΩ when measured from the sensor side of the connector—consistent with specifications. Same values are observed when measuring directly from the ECM/PCM connector. With engine running: AC voltage ranges from 0.1 to 10.00 volts on each knock sensor circuit. When the engine is running and measured at 20V scale, pins 11 and 51 (ECM/PCM side of the KS connector) show readings between 0.09 and 0.11 volts.

Based on these measurements, it appears that the ECM is not supplying sufficient voltage to the knock sensors—this could indicate a fault in the sensor signal circuit or an issue with the ECM itself, though alternator diode failure remains a possible root cause.