What does OBD code P0016 mean?
P0016 means the crankshaft and camshaft positions are out of alignment — the ECU has detected a correlation error between the crank and cam sensors. This usually indicates timing chain stretch, a worn timing chain tensioner, or a fault with the variable valve timing (VVT/VCT) system. Symptoms include rough idle, rattling from the engine (especially on startup), poor performance, and hard starting. This can be a serious fault — a badly stretched timing chain can snap and cause catastrophic engine damage.
Likely causes
Stretched or worn timing chain
A stretched chain allows the camshaft to lag behind the crankshaft — listen for rattling on cold start
Worn timing chain tensioner or guides
Plastic tensioner or guides wear out and allow chain to slap, causing the correlation error
VVT/VCT actuator fault
Variable valve timing actuator on the camshaft can fail or become stuck with old, dirty oil
Camshaft position sensor fault
A faulty cam sensor will cause the correlation to appear wrong even if timing is mechanically correct
Oil sludge blocking VVT system
Old, degraded oil blocks VVT passages — oil change and flush often resolves this
Repairs you may need
Typical cost range: £300–£1200 — Timing chain kit: £400–1,200 fitted depending on vehicle. VVT actuator: £200–500. Oil change: £60–120.
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