P25E4: B Camshaft Position - Unable to Achieve Locked Position Bank 1
What to do
Mention any rattle or knock from the engine for a second or two immediately after starting, even if it has been there a long time and you had stopped noticing. That noise is the most useful clue for this fault — it is the camshaft mechanism moving before oil pressure has locked it in place.
Say when the oil was last changed and what grade went in. Oil condition and viscosity explain more of this family of faults than any part does, and an oil change with the correct grade is a genuine first step here rather than a brush-off.
Say whether it is worse after the car has stood overnight than after a short stop, which fits oil draining back.
Do not leave a startup rattle indefinitely. The same low oil pressure at startup is hard on the timing chain, and that is a much larger repair.
What this code means
The exhaust camshaft phaser on bank 1 cannot reach the position where its lock pin engages.
This code names a mechanism the corpus explains elsewhere, and it is the clearest statement of it: the phaser lock pin. A variable valve timing phaser is moved by oil pressure — and at cranking speed there is almost none. A phaser left free would drift wherever the valve springs pushed it, so a spring-loaded pin locks it at a defined park position whenever oil pressure is low, and oil pressure releases the pin once the engine is running.
That park position is chosen so the engine starts reliably. This code says the phaser cannot get back to it — so the next start begins with the camshaft somewhere it should not be.
The causes divide into whether the phaser cannot move there, or the pin cannot engage when it arrives:
- Oil pressure not falling as it should at shutdown, so the phaser is still being held off park. Wrong or degraded oil is the commonest reason.
- A worn pin, a weak spring, or a bore worn oval, so the pin no longer drops in.
- Debris or sludge in the phaser, which is again an oil condition problem.
The audible tell is the same as its sibling and worth asking about: a brief rattle for a second or two on startup. That is the phaser moving against its stops before oil pressure arrives, and owners accept it as normal long before a code appears.
Start with the oil. Grade, condition and level explain more of this family than any part does.
Likely causes
Start here
- Worn camshaft phaser · specialist
- Incorrect oil grade or degraded oil · easy
- Clogged camshaft solenoid oil screen · easy
Less common
- Failed camshaft oil control solenoid · moderate
- Low engine oil level · easy
Symptoms
Components involved
Information, not instruction
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