The knock sensor is a piezoelectric structure-borne sound sensor bolted to the engine block; the module evaluates its signal per cylinder and retards ignition when it detects knock. Sensor C is a third sensor on engines with three or four knock sensors (documented on the McLaren 12C V8 and in Ford's 2020–23 systems). With a fault the module retards ignition across the board as protection – noticeable loss of power and higher consumption. P032B means the circuit is electrically sound but the signal is implausible. GM sets it when the filtered background noise stays below a threshold – typically a loose sensor or one not bolted down properly – in the first trip; Saab's GM-based engines also when excessive knock persists on several cylinders or a whole bank for 8–10 s. Ford does not use this code. Only McLaren lists this code for its four-sensor V8; thresholds follow the sensor A/B checks.
Medium severity. Can I keep driving?You can drive in moderation without pushing the engine. If you hear knocking, avoid full-throttle acceleration.
Symptoms
- Check engine light on
- Loss of power, sluggish response from ignition retard
- Higher fuel consumption
Most likely causes
- Sensor loose, wrongly torqued or mounted with sealant or on a dirty surface
- Engine software or calibration (bulletins for some models)
- Genuine knock on a whole bank or mechanical noise
- Sensor aged or damaged (low sensitivity)
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P032B means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 3: Ignition and misfires
- 2B: Specific fault in that system
Frequently asked questions
Can I keep driving with code P032B?
You can drive in moderation without pushing the engine. If you hear knocking, avoid full-throttle acceleration.
What causes code P032B?
The most common causes are: sensor loose, wrongly torqued or mounted with sealant or on a dirty surface; engine software or calibration (bulletins for some models); genuine knock on a whole bank or mechanical noise.
Related codes
- P032AKnock/Combustion Vibration Sensor C Circuit
- P032CKnock/Combustion Vibration Sensor C Circuit Low
- P032DKnock/Combustion Vibration Sensor C Circuit High
- P033BKnock/Combustion Vibration Sensor D Circuit Range/Performance
- P0324Knock/Combustion Vibration Control System Error
Sources
- static.nhtsa.gov: MC 10180034 0001
- gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
- law.cornell.edu: 13 CCR 1968.2
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.