P05CF

What it means

P05CF is a generic code meaning the engine control unit has seen the bank 2 camshaft timing perform poorly during the cold start strategy. The actual camshaft position, measured against the crankshaft signal, did not follow the commanded timing while the engine was cold. The 'B' camshaft is normally the exhaust cam on that bank, though the exact designation depends on the engine.

Symptoms

• Engine management light on
• Rough or unstable idle just after a cold start
• Hesitation or reduced power when cold
• Rattling or ticking noise from the top of the engine on start-up
• Poor fuel economy
• Occasional hard starting or extended cranking

Possible causes

• Low, dirty or incorrect grade engine oil, or oil sludge restricting the variable valve timing systemlikely
• Faulty or sticking camshaft phaser actuator or oil control solenoid on bank 2likely
• Wiring or connector fault in the solenoid or camshaft position sensor circuit, such as chafing, corrosion or poor terminal tensionpossible
• Faulty camshaft or crankshaft position sensor giving an inaccurate signalpossible
• Stretched timing chain, worn tensioner or guides, or incorrect mechanical timingpossible
• Blocked oil passage or screen in the valve timing oil feed, or low oil pressurepossible
• Faulty engine control unit or outdated software calibration, where the manufacturer has issued an update for this faultrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting coolant temperature, engine speed and load when the fault set. Check for related cam timing codes on either bank.
2. Check the oil level, condition and grade against the manufacturer's specification, and check the service history for overdue oil changes.
3. Visually inspect the wiring and connectors to the bank 2 oil control solenoid and camshaft sensors for damage, oil contamination, corrosion or loose pins.
4. Using a scan tool, compare commanded and actual cam angle on bank 2 at cold idle and as the engine warms, and compare with bank 1.
5. Test the oil control solenoid resistance and operation against the manufacturer's data, and check the sensor signals with a scope if available.
6. Remove and inspect the solenoid and its filter screen for debris or sludge, and check it moves freely.
7. Measure oil pressure if the phaser or solenoid checks pass, as the procedure and specification depend on the engine.
8. Check timing chain stretch and correlation using live data or by inspection, following the procedure for the specific engine.

How to fix

• Change the oil and filter to the correct grade and specification, and top up to the right level.
• Replace the faulty bank 2 oil control solenoid or camshaft phaser, cleaning the oil feed passages and screens.
• Repair or replace damaged wiring, connectors or terminals in the affected circuit.
• Replace a faulty camshaft or crankshaft position sensor once testing confirms it.
• Replace the timing chain, tensioner and guides and set the timing correctly if wear or incorrect timing is found.
• Apply a manufacturer software update only if a known calibration issue applies to the vehicle.

Can I keep driving?

Nearby codes

• P05CEGenericCold Start B Camshaft Position Timing Performance Bank 1
• P05D0GenericDriver Mode Select Switch A Circuit