P0018

What does P0018 mean?

P0018 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A).

This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.

Symptoms commonly associated with this code

Symptoms that drivers often report alongside this code. Not all may apply to every case:

• • Engine warning light on the dash, sometimes with the engine dropping into limp mode
• • Rough, lumpy idle that's most obvious when you pull up at a junction
• • Rattle or chain noise from the front of the engine on a cold start, dying down after a few seconds
• • Sluggish acceleration and a general lack of power
• • Hard starting, worse first thing in the morning
• • Fuel economy creeping up if the timing is meaningfully off

Possible causes

Causes commonly associated with P0018, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.

1. 1. Stretched timing chain on Bank 2, the usual suspect on higher-mileage V6 and V8 petrols where the chain and guides have worn. Common on VAG 2.4/3.2 V6 and some BMW N-series units that eat chains
2. 2. Sticking or clogged VVT solenoid on Bank 2, often the cheapest real fix. Old gummed oil blocks the oilways and the cam can't phase properly
3. 3. Low or sludged engine oil, or the wrong viscosity. The whole variable timing system runs on oil pressure, so neglected servicing causes this more than people expect
4. 4. Worn or failed timing chain tensioner or guides letting the chain go slack and the timing slip a few degrees
5. 5. Faulty Bank 2 Sensor A camshaft position sensor reading wrong, so the mechanical timing is fine but the ECU thinks it isn't
6. 6. Crankshaft position sensor sending dodgy data, less common but it skews the correlation
7. 7. Damaged wiring or a corroded connector on the cam or crank sensor circuit

How mechanics typically diagnose

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.

1. 1. Check the oil level and condition before anything else. Pull the dipstick. If it's low, black, or thick as treacle, an oil and filter change with the correct grade can clear a borderline P0018 outright, and it's daft to chase anything else until the oil is right
2. 2. Read live data and watch the cam to crank correlation angle on Bank 2. A deviation past roughly 5 degrees points at a mechanical timing problem rather than a sensor
3. 3. Inspect the cam and crank sensor connectors and wiring for corrosion, chafing, or a loose pin. Wiggle-test them with the engine idling
4. 4. Test the camshaft position sensor on Bank 2, around 500 to 1,200 ohms on most types, or swap it with the Bank 1 sensor and see if the fault jumps banks
5. 5. Command the Bank 2 VVT solenoid through your scan tool and listen for it clicking, or pull it out and check it isn't blocked with sludge
6. 6. If the oil, sensors, and solenoid all check out, you're into the timing chain. Listen for chain rattle on cold start and compare cam timing against the crank with the front cover off if needed

Common questions about P0018