P0332 indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the Knock Sensor B circuit, meaning the sensor signal is weaker than expected or the circuit is open.
The sensor itself has failed internally, producing little or no voltage.
Broken wires, cracked insulation, or corroded pins in the sensor circuit can cause a low‑voltage reading.
If the sensor was installed with an incorrect gap to the engine block, its output voltage can drop below the PCM’s threshold.
A poor engine block ground or a failed PCM reference voltage can make the sensor signal appear low.
Rarely, the PCM’s internal amplifier for the knock sensor can fail, but this is usually a last‑resort diagnosis.
It is possible but uncommon. Most P0332 codes are caused by the sensor, its wiring, or installation issues. Replacing the PCM should be considered only after confirming that the sensor and circuit are functioning correctly.
Replacing the sensor often resolves the issue, but only if the sensor itself is faulty. If the wiring or grounding is the problem, the code will persist until those issues are addressed.
The engine may run in a conservative mode to protect against knock, resulting in reduced power and fuel economy. It is advisable to diagnose and repair the problem promptly to avoid potential engine damage.
The PCM stores the fault code until it completes a set of drive cycles without detecting the condition again. Clear the code with a scan tool and drive the vehicle for several cycles to verify the repair.