Cold Start Rough Idle
The ECU detects rough idle behaviour during the cold-start phase only. Once the engine has warmed up the issue disappears. Typically caused by injector deposits, low compression on one cylinder when cold, or sticky valve guides.
Affected components
- Fuel injectors
- Cylinder compression
- Valve guides
Common causes
- High likelihood: Injector tip coked - poor cold spray pattern
- Medium likelihood: Valve guide sticky when cold
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.