Which camshaft is camshaft B?

On the overwhelming majority of twin-cam engines, A is the intake camshaft and B is the exhaust camshaft, and on a single-cam engine A is the only camshaft there is. The letters are defined by the manufacturer rather than fixed by the standard, though, so on an unusual engine it is worth confirming from the manufacturer's data before buying a solenoid or a phaser. Getting it wrong means working on the wrong side of the cylinder head.

What is the difference between P0011 and P0014?

They are the same fault on different camshafts of the same bank. P0011 concerns camshaft A, normally the intake, and P0014 concerns camshaft B, normally the exhaust. The causes overlap almost entirely — oil condition, a blocked or sticking oil control valve, a worn phaser, low oil pressure — but each camshaft has its own solenoid and its own phaser, so the parts are not interchangeable. The symptoms differ slightly too: an exhaust phaser stuck in the wrong place usually shows as an unstable idle, because exhaust valve timing controls how much burnt gas is left in the cylinder.

Can dirty oil cause a P0014 code?

Yes, and it is the most common cause. The camshaft phaser is a hydraulic device moved by engine oil, and the oil reaches it through a solenoid valve with a fine gauze screen. Oil that is overdue, contaminated or of the wrong viscosity will not flow through that screen properly, so the phaser stops responding to commands. An oil and filter change to the exact specification, with the solenoid screen cleaned at the same time, resolves a large share of these codes.

Will P0014 fail an MOT?

Yes. An illuminated engine management lamp is a major defect on petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, and that single defect accounts for 371,859 failures in the DVSA data behind this site. Cam timing faults are also more likely than most to fail the emissions readings independently, because valve timing changes the hydrocarbon and lambda figures the test measures.

Powertrain code · standard

P0014Exhaust camshaft timing too far advanced, bank 1

Standard definition: "B" Camshaft Position - Timing Over-Advanced (Bank 1)

Last updated 27 July 2026

Quick answer

The camshaft the control unit calls B on bank one, which on almost every twin-cam engine is the exhaust camshaft, is phased further advanced than commanded. The causes come from the same family as the intake side, but the symptoms are distinctive because exhaust cam phasing is what many modern engines use in place of a conventional exhaust gas recirculation valve.

How the car works this out

Same principle as the intake codes: the control unit compares the phaser angle it commanded with the angle it measures from the camshaft and crankshaft sensors, and stores a code when the two disagree by more than the tolerance for longer than the allowed time. Two things are worth knowing about the exhaust side specifically. Exhaust phasers commonly rest in the fully advanced position rather than the fully retarded one, which is why the over-advanced code is the usual exhaust-side complaint when oil is not getting through. And the letters are defined per manufacturer rather than universally, so while B is the exhaust camshaft on the overwhelming majority of engines, it is worth confirming for yours before ordering a solenoid.

What you might notice

A lumpy, hunting or unstable idle, often more noticeable than the loss of power
Hesitation off idle and a general flatness in ordinary driving
Worse fuel consumption
The engine management lamp on, sometimes with a reduced power warning
On some engines a brief rattle after a cold start as the phaser fails to lock

What causes it

Most likely first. A code names the check that failed, not the part that failed it, so more than one of these can produce the same number.

1Dirty, overdue or wrong-viscosity engine oil, which is where the diagnosis starts on every variable valve timing codeCommon
How to check: Change it to the exact specification with a new filter, clear the code and drive it. Nothing further should be bought until this has been done.
2The exhaust bank's oil control valve sticking, or its gauze filter screen cloggedCommon
How to check: Note that a twin-cam engine has a separate solenoid for each camshaft. Make sure the exhaust one is the one being tested, not the intake one that happens to be easier to reach.
3Sludge or debris restricting the oil feed to the exhaust phaserPossible
4A worn exhaust phaser that can no longer hold its commanded positionPossible
5Low oil pressure from a low level or a tired pumpPossible
6Wiring or connector damage at the exhaust camshaft solenoidPossible
7On engines where the high-pressure fuel pump is driven from a lobe on this camshaft, wear at the pump follower altering what the sensor seesLess common
How to check: Look for fuel pressure codes stored alongside. If they are there, have the pump follower and its lobe inspected rather than only the phaser.

What to do about it

1Change the oil and filter to the manufacturer's exact specification first, and have the exhaust camshaft solenoid removed and its screen cleaned at the same time.
2Make sure whoever is working on it is dealing with the exhaust camshaft rather than the intake. A twin-cam engine has two solenoids and two phasers, and B is not always the one nearest to hand.
3Have the solenoid commanded on a diagnostic tool while watching the exhaust cam angle on live data. A phaser that does not respond to the command tells you a great deal in a few seconds.
4Check whether any fuel pressure codes are stored with it, since on some engines the fuel pump is driven from this camshaft and a worn follower can be behind both.

Can you keep driving?

Briefly, gently

The engine will run, and the usual complaint is a poor idle rather than anything alarming. Do not treat it as permanent: the phaser is being starved of clean oil, and the same lack of oil flow is not doing the rest of the engine any good either. If the idle is bad enough to stall in traffic, that is its own hazard and worth dealing with quickly.

Will it fail an MOT?

Exhaust valve timing changes how much burnt gas stays in the cylinder for the next cycle, which is precisely the quantity many engines use to control combustion temperature and emissions internally. Get it stuck in the wrong place and the effect lands squarely on the readings the fast idle test takes, so this is one of the code families genuinely likely to fail the gas test as well as the lamp test. The lamp itself is a major defect on petrol cars first used from 1 July 2003 and diesels from 1 July 2008, so the outcome is the same regardless of what the exhaust probe reads.

The light this turns on

Engine management lightThe engine management system has found a fault it cannot correct and has stored a code for it. The car will usually still drive, but an illuminated engine light is an automatic MOT failure on petrol cars first used from 1 July 2003 and diesels from 1 July 2008.

Common questions

Which camshaft is camshaft B?: On the overwhelming majority of twin-cam engines, A is the intake camshaft and B is the exhaust camshaft, and on a single-cam engine A is the only camshaft there is. The letters are defined by the manufacturer rather than fixed by the standard, though, so on an unusual engine it is worth confirming from the manufacturer's data before buying a solenoid or a phaser. Getting it wrong means working on the wrong side of the cylinder head.
What is the difference between P0011 and P0014?: They are the same fault on different camshafts of the same bank. P0011 concerns camshaft A, normally the intake, and P0014 concerns camshaft B, normally the exhaust. The causes overlap almost entirely — oil condition, a blocked or sticking oil control valve, a worn phaser, low oil pressure — but each camshaft has its own solenoid and its own phaser, so the parts are not interchangeable. The symptoms differ slightly too: an exhaust phaser stuck in the wrong place usually shows as an unstable idle, because exhaust valve timing controls how much burnt gas is left in the cylinder.
Can dirty oil cause a P0014 code?: Yes, and it is the most common cause. The camshaft phaser is a hydraulic device moved by engine oil, and the oil reaches it through a solenoid valve with a fine gauze screen. Oil that is overdue, contaminated or of the wrong viscosity will not flow through that screen properly, so the phaser stops responding to commands. An oil and filter change to the exact specification, with the solenoid screen cleaned at the same time, resolves a large share of these codes.
Will P0014 fail an MOT?: Yes. An illuminated engine management lamp is a major defect on petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, and that single defect accounts for 371,859 failures in the DVSA data behind this site. Cam timing faults are also more likely than most to fail the emissions readings independently, because valve timing changes the hydrocarbon and lambda figures the test measures.

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