OBD-II Code P0018 — What It Means & How to Fix It

What Does This Error Mean?

P0018 means the crankshaft and intake camshaft positions don't match on Bank 2. Your engine's computer watches both sensors to confirm timing is correct. When the two readings disagree, it stores this code. Common causes include a stretched timing chain, worn tensioner, or a bad sensor. You may notice rough idle, poor acceleration, or a rattling noise from the engine.

Affected Models

All vehicles 1996+
Common in Chevrolet Malibu
Common in GMC Acadia
Common in Pontiac G6
Common in Saturn Vue

Common Causes

Stretched or worn timing chain that has slipped on the camshaft sprocket
Faulty intake camshaft position sensor on Bank 2 giving wrong readings
Low or dirty engine oil reducing variable valve timing actuator performance
Worn timing chain tensioner allowing excessive chain slack
Damaged or misaligned reluctor wheel on the camshaft

How to Fix It

Check your engine oil level and condition right away. Pull the dipstick and look at the color and level. Dark, sludgy oil or low oil level can trigger this code by starving the VVT actuator.

Use the oil viscosity listed in your owner's manual. Thin or dirty oil is a very common cause of timing-related codes.
Listen carefully at startup for a rattle or slapping sound from the front of the engine. This noise usually appears in the first few seconds before oil pressure builds up fully.

Timing chain rattle is loudest on cold starts and may quiet down as the engine warms. Don't ignore it — the chain may already be stretched.
If no rattle is present, locate the Bank 2 intake camshaft position sensor. It is usually bolted to the cylinder head near the intake side of the engine. Disconnect and inspect the connector for corrosion or damage.

Bank 2 is the side of the engine opposite cylinder 1. On many V6 and V8 engines, that is the passenger side.
Test the sensor resistance with a multimeter if you have one. Compare the reading to your vehicle's service specification. A sensor that is out of spec should be replaced.

Camshaft position sensors typically cost $20-$60 at an auto parts store and are straightforward to swap out.
Clear the code and drive the vehicle for a full warm-up cycle. If P0018 returns with rattle noise, the timing chain needs replacement. If it returns without noise, replace the camshaft sensor first.

Continuing to drive with a bad timing chain puts your engine at serious risk. Don't delay if the rattle is present.

When to Call a Professional

P0018 often points to a timing chain problem that needs professional diagnosis. If the engine rattles on startup, stop driving and call a mechanic. A skipped timing chain can destroy engine valves in an interference engine. Diagnosis typically costs $100-$200 with a professional scan tool. Timing chain replacement can run $900-$2,200 depending on your vehicle.

Frequently Asked Questions

What does Bank 2 mean?

Bank 2 is the side of the engine that does NOT contain cylinder number 1. On most V6 and V8 engines, Bank 2 is the passenger side. On four-cylinder engines, there is only one bank, so P0018 is rare. Your vehicle's repair manual will confirm which side is Bank 2.

Can I still drive with P0018?

You can drive short distances if the engine is not rattling and runs smoothly. But P0018 should be diagnosed and fixed soon — within a week or two. If you hear a rattle or the engine feels rough, stop driving immediately. Ignoring a stretched timing chain risks serious and expensive engine damage.

Does P0018 always mean the timing chain is bad?

No — not always. A dirty or low oil level is a very common and cheap fix. A bad camshaft position sensor can also cause this code. Only if those checks fail should you suspect the timing chain itself. A mechanic with a scan tool can check timing chain stretch accurately.