What it means
The knock sensor signal voltage is below the expected range. Usually points to a piezoelectric sensor that has lost its output, or a short to ground in the signal line.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Knock sensor 1 detects combustion vibration on bank 1 and sends its signal to the engine control module. P0327 sets when that circuit's signal is below the expected level, which can happen if the sensor output is lost or the signal wire is shorted to ground.
Common causes
Most likely first.
- Knock sensor failed
- Signal wire shorted to ground
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Power loss from defensive spark retard
- Increased fuel consumption
- Possible audible pinging under load
How to diagnose it
- Check freeze-frame data and live knock-sensor readings to confirm the low signal and identify the conditions when it appears.
- Inspect knock sensor 1 on bank 1 and its connector for corrosion, water, damaged pins, or a loose fit.
- Trace the sensor signal wire for chafing or contact with ground, paying particular attention near the sensor and hot engine surfaces.
- Test the circuit for a short to ground and continuity between the sensor and control module using the circuit diagram and manufacturer's procedure.
- If the wiring and connector pass inspection, test the sensor output and replace the sensor only if it fails the manufacturer's test.
Common fixes
- Clean or repair corroded connector pins and restore a secure connection.
- Repair the signal wire shorted to ground.
- Replace knock sensor 1 on bank 1 if its output is below specification.
Can I keep driving?
Drive only gently and avoid high loads or towing; the module may retard ignition timing, reducing power, while knock protection may be compromised. Stop if pinging is audible under load.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.