Which side of the engine is bank 2?

Bank two is simply the bank that does not contain cylinder one, and where cylinder one sits varies by manufacturer, so there is no universal left or right answer. On many transverse V6 installations bank two turns out to be the rear bank against the bulkhead, but that is a tendency rather than a rule and plenty of engines are the other way round. Check the numbering for your engine before removing anything, because on a V engine a wrong guess means a wasted strip-down on the opposite side.

I have P0011 and P0021 stored together — what does that mean?

It means the problem is almost certainly the oil, not the phasers. The two banks have separate phasers and separate control valves, so both failing in the same way at the same time is not a coincidence: they share the oil that drives them and the pump that supplies it. Check the oil level, change the oil and filter to the exact specification the manufacturer lists, and have the oil pressure checked if the level was correct. Replacing two phasers on the strength of these codes is an expensive way to find that out.

Can an inline four-cylinder engine set P0021?

No. Bank two only exists on an engine with two cylinder banks — a V, a flat or a W layout — so an inline engine has nothing to report. If a reader shows P0021 on a four-cylinder inline car, check the code with a different tool, because the likeliest explanations are a misread or a generic scanner mapping a manufacturer-specific code onto the wrong definition.

Will P0021 fail an MOT?

Yes. An illuminated engine management lamp is a major defect for petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, and it is the largest warning-lamp defect in the DVSA data behind this site with 371,859 recorded failures. Valve timing sitting in the wrong place also tends to push the hydrocarbon and lambda readings outside the limits at the fast idle emissions test, which is a separate failure.

Powertrain code · standard

P0021Camshaft timing stuck too far advanced, bank 2

Standard definition: "A" Camshaft Position - Timing Over-Advanced (Bank 2)

Last updated 27 July 2026

Quick answer

The same fault as P0011, on the other cylinder bank. Two useful things follow. The engine must be a V, a flat or a W, because an inline engine has only one bank. And if the bank one code is stored alongside it, the problem is almost certainly the oil both phasers share rather than two phasers failing on the same day.

How the car works this out

The check is identical to bank one: commanded phaser angle against the angle measured from that bank's camshaft sensor and the crankshaft sensor, with a tolerance and a time limit. What changes is the interpretation. Bank two is defined as the bank that does not contain cylinder one, so it is not reliably the rear bank, the left bank or any other fixed position — it depends on where the manufacturer put cylinder one. On many transverse V6 installations bank two is the rear bank against the bulkhead, which makes the same part considerably dearer to fit in labour terms, but that is a tendency rather than a rule.

What you might notice

A rough or hunting idle, sometimes with a slight imbalance you can hear between the two banks
Hesitation and a flat spot low down
Higher fuel consumption
The engine management lamp on, occasionally with reduced power

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-grade oil, particularly likely if the bank one code P0011 is stored alongside this oneCommon
How to check: Two banks failing at the same moment is not a coincidence, it is a shared supply. Change the oil and filter to the exact specification before considering any part on either bank.
2The bank two oil control valve sticking or its screen blockedCommon
How to check: Make sure the correct bank's solenoid is the one being removed. On a V engine the two look identical and only one of them is relevant.
3Low oil pressure, from level, pump wear or a partially blocked pickupPossible
4Wiring or connector damage on the bank two harness, which on many V engines is the longer run and the one closer to the exhaustPossible
5A worn phaser on that bankPossible
6A stretched secondary chain on that bank, on the V engines that drive each bank's camshafts through its own chain from a primary driveLess common
How to check: Look for a correlation code for the same bank stored alongside, and for a rattle at cold start that seems to come from one side of the engine.

What to do about it

1Establish which bank is bank two on your engine before anything is removed. It is the bank that does not contain cylinder one, and the manufacturers do not agree on where cylinder one lives.
2If P0011 is stored alongside P0021, stop thinking about phasers and start with the oil. Both banks failing together points at the supply they share.
3Change the oil and filter to the exact specification, and clean the screen on the bank two control valve.
4If it is still there afterwards, have the solenoid commanded on a diagnostic tool and the cam angle watched on live data before anything deeper is opened up.

Can you keep driving?

Briefly, gently

The car runs, down on power and economy, and there is no immediate danger unless the underlying problem is low oil pressure rather than a sticky valve. Check the oil level yourself before you drive anywhere. If both banks have thrown timing codes together, treat that as a warning about oil supply and get it looked at rather than continuing to run it.

Will it fail an MOT?

The lamp rule is written by date of first use, not by how many banks or cylinders the engine has, so a large V6 or V8 is caught by exactly the same major defect as a small hatchback: petrol cars first used from 1 July 2003, diesels from 1 July 2008. Bank two faults do have one practical MOT consequence of their own. A V engine has a catalytic converter and a lambda sensor per bank, and a bank running with its valve timing out will drag that bank's readings off, which the single tailpipe probe sees as a raised hydrocarbon figure and a lambda value outside the narrow band around 1.00 the test allows.

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 side of the engine is bank 2?: Bank two is simply the bank that does not contain cylinder one, and where cylinder one sits varies by manufacturer, so there is no universal left or right answer. On many transverse V6 installations bank two turns out to be the rear bank against the bulkhead, but that is a tendency rather than a rule and plenty of engines are the other way round. Check the numbering for your engine before removing anything, because on a V engine a wrong guess means a wasted strip-down on the opposite side.
I have P0011 and P0021 stored together — what does that mean?: It means the problem is almost certainly the oil, not the phasers. The two banks have separate phasers and separate control valves, so both failing in the same way at the same time is not a coincidence: they share the oil that drives them and the pump that supplies it. Check the oil level, change the oil and filter to the exact specification the manufacturer lists, and have the oil pressure checked if the level was correct. Replacing two phasers on the strength of these codes is an expensive way to find that out.
Can an inline four-cylinder engine set P0021?: No. Bank two only exists on an engine with two cylinder banks — a V, a flat or a W layout — so an inline engine has nothing to report. If a reader shows P0021 on a four-cylinder inline car, check the code with a different tool, because the likeliest explanations are a misread or a generic scanner mapping a manufacturer-specific code onto the wrong definition.
Will P0021 fail an MOT?: Yes. An illuminated engine management lamp is a major defect for petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, and it is the largest warning-lamp defect in the DVSA data behind this site with 371,859 recorded failures. Valve timing sitting in the wrong place also tends to push the hydrocarbon and lambda readings outside the limits at the fast idle emissions test, which is a separate failure.

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