Powertrain, generic · Fuel and air metering, auxiliary emission controls

P0025 "B" Camshaft Position - Timing Over-Retarded (Bank 2)

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modePossible

The engine control module compares the commanded position of the exhaust camshaft on bank 2 with the actual position from the camshaft and crankshaft sensors. This code is set when the camshaft stays further retarded than commanded for longer than a calibrated time. Usually the phaser does not move far enough out of its rest position, because oil pressure is too low to release the locking pin, the oil control valve does not open, or the oil screen is blocked. A stretched timing chain also shifts the camshaft towards retarded. Bank 2 exists only on V and boxer engines; it is the cylinder bank without cylinder 1.

Likely causes

Oil pressure or oil level too low, oil worn out

Oil control valve sticking closed or its screen blocked

Cam phaser defective or seized in its rest position

Timing chain stretched or jumped a tooth

Wear debris in the oil circuit, e.g. from a thrust bearing

Symptoms

Check engine light on
Noticeably less torque and pulling power
Higher fuel consumption
Harder starting in some cases
Rattle from the timing drive if the chain is stretched

Repair estimate

DifficultyMediumDIY possible

Parts and labour€60–2,500

Time0–10 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cam phaser exhaust bank2oil control valve exhaust bank2engine oiltiming chain

References: law.cornell.edu, saabwisonline.com, patents.google.com, en.wikipedia.org.