Applicable Systems
OBD-II
Symptoms
Knock sensor signal circuit malfunction; ECM cannot detect engine knock; ignition timing may be retarded for protection.
Possible Causes
- Knock sensor internal failure
- Sensor wiring open/short
- Sensor connector corrosion
Troubleshooting Steps
- Step 1: Check knock sensor resistance (1-5 megohm typical)
Resistance within range - Step 2: Inspect sensor wiring for damage
Wiring intact - Step 3: Check sensor connector
Connector clean - Step 4: Replace knock sensor if faulty
New sensor signal present - Step 5: Clear code and verify timing advance
Timing advances normally
How to Reset
Clear with OBD-II scanner after sensor replacement.
Common Replacement Parts
- Knock Sensor (OEM spec)
Frequently Asked Questions
- Q: What does knock sensor do?
Detects engine knock (detonation/pre-ignition). ECM retards timing when knock detected to prevent engine damage. Failed sensor means no knock protection.
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Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II
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