P0325
Knock Sensor 1 Circuit Malfunction
medium
i Description
The knock sensor 1 circuit has a malfunction. The knock sensor detects engine knock (detonation) and signals the ECU to retard ignition timing to prevent engine damage. Without it, the ECU runs conservative timing, reducing performance.
? Common Causes
- Faulty knock sensor
- Damaged wiring or connector
- Knock sensor not torqued correctly
- Engine mechanical noise triggering sensor
- Corroded connector
! Symptoms
- Check engine light
- Reduced engine performance
- Slightly worse fuel economy
- Engine may ping under load with low-octane fuel
# Diagnostic Steps
- Inspect knock sensor wiring and connector
- Test knock sensor resistance (consult manufacturer specs)
- Verify sensor is properly torqued
- Tap near the sensor with engine running — should see ECU response on scan tool
- Replace sensor if no signal
⚙ Typical Fix
Replace the knock sensor. Ensure correct torque during installation.
Parts Needed
Knock sensor, Knock sensor harness (if corroded)
Estimated Cost
$100-$400
↔ Related Codes
Q Frequently Asked Questions
Yes, but the ECU will retard timing as a precaution, reducing power. Use higher-octane fuel to reduce knock risk until it is fixed.
Knock sensor: $30-$100. On some engines the sensor is buried under the intake manifold, increasing labour to $200-$400.
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