Where is cylinder 2 on my engine?

On an inline engine, cylinder two is the second along from the timing belt or chain end, which is the end furthest from the gearbox on almost all of them. On a V6 it depends on the manufacturer: many Japanese and General Motors V6s alternate the numbering between banks, putting cylinder two opposite cylinder one, while Ford and Honda V6s number down one bank first, putting cylinder two beside cylinder one. Because bank one is defined as the bank containing cylinder one, guessing here means working on the wrong side of the engine.

Can a head gasket cause a P0302 code?

Yes, and it is a real possibility rather than a remote one when P0302 and P0303 are stored together. On an inline four the strip of metal between the two middle bores is the narrowest and hottest part of the block, so that is where a head gasket usually fails first, and it lets compression escape from both cylinders at once. Confirm it with a combustion gas test on the coolant, a cooling system pressure test, or a compression test showing the two middle cylinders low while the outer two read normally.

Should I replace all the coils or just the one for cylinder 2?

Replace the one that has failed and keep the old one as a known-working spare for future swap testing. Coils do not wear as a set the way spark plugs do, so replacing all of them is money spent on parts that were working. The exception is a high-mileage engine where coils have already failed one after another, since that pattern usually means they are all near the end of their life. Spark plugs are the opposite case and should always be done as a complete set.

Will a P0302 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 defect records 371,859 failures in the DVSA data behind this site. A misfiring cylinder will also usually push the hydrocarbon reading over the limit at the emissions test, so the car often fails on both.

Powertrain code · standard

P0302Cylinder 2 is misfiring

Standard definition: Cylinder 2 Misfire Detected

Last updated 27 July 2026

Quick answer

Cylinder two is missing combustion events. On a four-cylinder engine it is one of the two middle cylinders, which matters because the middle of the block is where head gaskets fail first — and on a V engine, cylinder two may not even be on the same bank as cylinder one.

How the car works this out

The detection is identical for every per-cylinder code: crankshaft deceleration after each firing event, attributed to a cylinder using the camshaft signal, counted until a threshold is crossed. What distinguishes P0302 is only where cylinder two physically sits, and that is not where people assume. On many Japanese and General Motors V6s the numbering alternates between banks, so cylinder two is on the opposite side of the engine to cylinder one. On Ford and Honda V6s it runs down one bank first, so cylinder two is next door to cylinder one. Get that wrong and you spend an afternoon replacing a perfectly good coil on the wrong side of the engine.

What you might notice

An uneven idle, often felt more as a shudder than heard as a change in note
A stumble under acceleration that comes and goes with load
The engine management lamp on steady, or flashing if the cylinder is fully dead
If it is a head gasket rather than a coil: coolant disappearing with no visible leak, and the header tank bubbling or pressurising quickly

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.

1The ignition coil for cylinder twoCommon
How to check: Swap it with the coil from cylinder one, its immediate neighbour on an inline four, and see whether the code moves with it.
2A worn or fouled spark plug, or oil in the plug well from a leaking cam cover gasketCommon
3A blocked or leaking injector on that cylinderPossible
4A failing head gasket between cylinders two and three, which is where gaskets on an inline four normally let goPossible
How to check: Take this seriously rather than as a remote possibility if P0303 is stored alongside P0302. The bridge of metal between the two middle bores is the narrowest and hottest part of the block. Confirm with a combustion gas test on the coolant, a cooling system pressure test, or a compression test that shows the two middle cylinders low together while the outer two are normal.
5Low compression in cylinder two on its own, from a burnt or tight exhaust valveLess common

What to do about it

1Confirm which cylinder is number two on your engine before ordering anything. On an inline four it is second from the timing drive end; on a V6 it depends entirely on whether your manufacturer alternates banks or fills one bank first.
2If P0303 is stored alongside it, pause before buying ignition parts. Two adjacent middle cylinders misfiring together is the signature of the head gasket between them, and a combustion gas test on the coolant takes minutes.
3Otherwise, swap the coil with a neighbour, then the plug, then the injector, checking after each whether the code follows the part.
4Look at the coolant level and the underside of the oil filler cap while the bonnet is up. Unexplained coolant loss or a creamy deposit turns a possible head gasket into a probable one.

Can you keep driving?

Only to a garage

As a coil or plug fault, it will get you to a garage on a steady lamp. If the misfire turns out to be a head gasket, the calculation changes completely: combustion pressure leaking into the cooling system leads to overheating, and an overheated engine is a far larger repair than the gasket. Any sign of coolant loss or a temperature gauge climbing means stopping.

Will it fail an MOT?

A misfire is one of the few MOT failures where the repair can realistically be done and the car retested the same day, which is worth knowing before you drive away from a failure. The catch is that a partial retest only covers what failed, and the lamp has to be out and stay out — clearing the code to extinguish it also resets the readiness monitors, which the tester can see. If the cause turns out to be a head gasket rather than a coil, plan on a proper repair and a fresh test rather than a same-day retest.

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

Where is cylinder 2 on my engine?: On an inline engine, cylinder two is the second along from the timing belt or chain end, which is the end furthest from the gearbox on almost all of them. On a V6 it depends on the manufacturer: many Japanese and General Motors V6s alternate the numbering between banks, putting cylinder two opposite cylinder one, while Ford and Honda V6s number down one bank first, putting cylinder two beside cylinder one. Because bank one is defined as the bank containing cylinder one, guessing here means working on the wrong side of the engine.
Can a head gasket cause a P0302 code?: Yes, and it is a real possibility rather than a remote one when P0302 and P0303 are stored together. On an inline four the strip of metal between the two middle bores is the narrowest and hottest part of the block, so that is where a head gasket usually fails first, and it lets compression escape from both cylinders at once. Confirm it with a combustion gas test on the coolant, a cooling system pressure test, or a compression test showing the two middle cylinders low while the outer two read normally.
Should I replace all the coils or just the one for cylinder 2?: Replace the one that has failed and keep the old one as a known-working spare for future swap testing. Coils do not wear as a set the way spark plugs do, so replacing all of them is money spent on parts that were working. The exception is a high-mileage engine where coils have already failed one after another, since that pattern usually means they are all near the end of their life. Spark plugs are the opposite case and should always be done as a complete set.
Will a P0302 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 defect records 371,859 failures in the DVSA data behind this site. A misfiring cylinder will also usually push the hydrocarbon reading over the limit at the emissions test, so the car often fails on both.

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