P000B: B Camshaft Position Slow Response Bank 1
What to do
Ask for the oil control solenoid's filter screen to be cleaned before anything is replaced. It is a fine mesh that blocks with sludge and it is the commonest cause — and the exhaust side, which this code names, runs hotter and clogs sooner than the intake side.
Say when the oil was last changed and what grade. Degraded or wrong-viscosity oil slows the phaser directly, so an oil change is a real diagnostic step here.
If an exhaust gas recirculation fault is also stored, mention it and ask whether they might be the same problem. This camshaft does some of the emissions work that EGR otherwise does, so one fault can produce both codes.
Say whether it is worse from cold, which points at oil rather than hardware.
What this code means
The exhaust camshaft phaser on bank 1 is moving to its commanded position too slowly.
Camshaft A is the intake and camshaft B is the exhaust, on almost every engine that has both — and knowing which is which is worth more than it sounds, because the exhaust phaser has a harder life.
It sits on the hot side of the head. Oil reaching it has already passed through the hottest part of the engine, so deposits form there first and its solenoid screen clogs sooner than the intake one. On an engine where only one phaser is complaining, this is frequently the one.
The exhaust phaser also does more of the emissions work, which is why this code is emissions-related rather than merely a driveability one. Retarding exhaust valve timing holds burnt gas in the cylinder — internal exhaust gas recirculation — which suppresses nitrogen oxide formation without an EGR valve moving at all. A slow exhaust phaser therefore raises NOx directly, and on some engines produces EGR flow codes as a side effect.
So a car with both an exhaust phaser code and an EGR code very often has one fault. Fix the phaser and re-check before touching the EGR system.
The diagnosis is the family's: solenoid screen first, oil grade and condition second, solenoid third, phaser last.
Likely causes
Start here
- Clogged camshaft solenoid oil screen · easy
- Incorrect oil grade or degraded oil · easy
- Failed camshaft oil control solenoid · moderate
Less common
- Worn camshaft phaser · specialist
- Low engine oil level · easy
Symptoms
Components involved
Information, not instruction
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