P0012Powertrain
Powertrain · SAE
Intake Cam Timing — Over-Retarded (Bank 1)
Meaning
The engine control module has detected that the Bank 1 intake camshaft timing is more retarded than the calculated target and cannot return to the correct position. The VVT actuator is unable to advance the intake camshaft sufficiently relative to its current position.
Common causes
- VVT solenoid (OCV) for Bank 1 intake clogged by oil sludge or carbon deposits
- Insufficient oil pressure (worn oil, weak pump, clogged filter) preventing phaser movement
- VVT vane-type phaser stuck in the retarded position due to wear or deposits
- Engine oil too viscous when cold or degraded, giving a slow actuator response
- Slack timing chain or belt causing the actual camshaft position to read incorrectly
- Incorrect CMP signal on Bank 1 producing a false position reading
Symptoms
- Check-engine light (MIL) illuminated
- Rough idle, especially with warm engine
- Torque loss at low RPM
- Increased fuel consumption
- In severe cases, mechanical noise from the timing-drive area
Severity
High: permanently retarded camshaft timing reduces power and increases emissions; a mechanically stuck phaser can damage the timing drive.
What to do
- Check engine oil level, quality, and pressure; replace oil and filter if degraded
- Clean or replace the VVT solenoid for Bank 1 intake
- Check timing chain or belt condition and tension
- Verify phaser response to ECM commands using live data
- If the phaser does not respond after cleaning the oil circuit, replace it