What does a P0316 code mean?

It means the engine misfired during roughly the first thousand crankshaft revolutions after a start, which is about the first half-minute of running. The control unit monitors that window separately because the catalytic converter is still cold and cannot deal with unburnt fuel, so misfires there matter more than the same misfires later. It is usually stored alongside a cylinder-specific code, and when it appears alone the misses could not be attributed to one cylinder.

Why does my car only misfire when I first start it?

Because something changes while the car stands. The three commonest are an injector that leaks fuel into a cylinder overnight and floods it, fuel pressure bleeding away through a failed check valve so the first start runs lean, and a valve that leaks when cold but seals once the cylinder head has warmed up and expanded. Worn spark plugs also fail cold before they fail warm, since a cold, rich mixture is the hardest thing to light. Note whether it happens on every start or only the first of the day, because that distinction narrows the list considerably.

Will P0316 fail an MOT if the car runs fine when it is warm?

Yes. The failure is for the lamp being illuminated, not for how the car behaves in the test bay. An illuminated engine malfunction indicator lamp is a major defect on petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, and the tester records it whatever the engine sounds like. Because the emissions readings are taken hot, cars with P0316 frequently pass the gas test and fail on the lamp alone.

Can a leaking injector cause P0316?

Yes, and it is one of the most common causes. An injector that does not seal properly drips fuel into its cylinder while the car is parked, so on the first start that cylinder is flooded and cannot fire cleanly until the excess has cleared. The tell-tale signs are a strong smell of petrol at the first start of the day, a stumble that lasts a few seconds and then vanishes, and a spark plug from that cylinder that is visibly wet when removed.

Powertrain code · standard

P0316Misfiring in the first few seconds after starting

Standard definition: Engine Misfire Detected on Startup (First 1000 Revolutions)

Last updated 27 July 2026

Quick answer

The engine misfired during roughly the first thousand turns of the crankshaft after a start, which is about the first half-minute of running. It is the one misfire code that can be set by a fault which then vanishes completely once the engine is warm.

How the car works this out

Misfire monitoring runs all the time, but the control unit treats the period immediately after a start as a separate case and counts misfires over roughly the first thousand crankshaft revolutions. It does that because a cold engine sitting in front of a cold catalytic converter is the worst possible moment for unburnt fuel: the converter is not yet hot enough to deal with anything, so those particular misses do far more damage to emissions than the same number would later in the journey. P0316 is that startup counter tripping. It usually appears with a cylinder code beside it, and when it appears on its own the control unit counted the misses but could not attribute them to one cylinder.

What you might notice

A stumble, shudder or brief rough patch for the first few seconds after starting, which then clears completely
It is often only the first start of the day, and never a restart an hour later
A puff of grey or black smoke and a smell of petrol at the first start
The engine management lamp on, on a car that then drives perfectly
Sometimes a slightly longer crank before it catches

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.

1Spark plugs near the end of their life, which cope with a warm engine but not with the cold, rich, damp conditions of a first startCommon
How to check: Check when they were last changed by date as well as mileage, and look at them. This is the cheapest thing on the list and it fixes a good share of these.
2An injector leaking down overnight and flooding one cylinder with fuel while the car standsCommon
How to check: The signature is a stumble and a smell of petrol on the first start of the day only. A fuel pressure gauge left connected overnight shows the rail pressure bleeding away, and the plug from the affected cylinder will be visibly wet.
3Fuel pressure bleeding away while parked through a failed check valve in the pump or a leaking regulator, so the first start runs lean until pressure buildsPossible
How to check: Same overnight gauge test. A slow crank-and-catch on the first start of the day with normal restarts afterwards fits this well.
4A weak ignition coil that manages a warm engine but cannot fire a cold, wet plugPossible
5Low compression from a valve that seals once the head has warmed and expanded but leaks when everything is cold, typically a slightly burnt or tight exhaust valvePossible
How to check: A compression test done stone cold, before the engine has run at all, compared against the same test once warm.
6Carbon on the inlet valves of a direct injection engine, which soaks up the first squirts of fuel on a cold startPossible
7On a diesel, worn glow plugs or a failing glow plug relay leaving the cylinders too cold to fire cleanlyPossible
8Oil in the spark plug wells from a leaking cam cover gasket, at its worst when everything is cold and dampLess common

What to do about it

1Pay attention to exactly when it happens. If it is only the first start of the day and never a restart, that points hard at something that changes while the car stands: fuel bleeding down, an injector leaking into a cylinder, or condensation in the ignition parts.
2Have the freeze frame data read as well as the code. It records the coolant temperature at the moment the fault was logged, and a code that only ever sets below a certain temperature is a very different investigation from one that sets at any temperature.
3Look for a cylinder code stored alongside. P0316 with P0303 is a cylinder three problem that only shows when cold; P0316 on its own is more likely to be fuel pressure or plugs across the set.
4Do not treat it as harmless because the car runs well once warm. A cold misfire is the most damaging kind for the catalytic converter, precisely because the converter is not yet hot enough to burn off what reaches it.

Can you keep driving?

Yes

An engine that misfires for a few seconds and then runs cleanly is not dangerous and will get you where you are going. The two reasons not to leave it are the catalytic converter, which takes the worst of a cold misfire, and the MOT, which the car cannot pass while the lamp is lit. Neither is urgent this week; both are certain.

Will it fail an MOT?

This is the code that catches people out, because by the time the car reaches the test centre it has been running for twenty minutes and is behaving perfectly. It makes no difference at all. The lamp is lit from the stored code, and an illuminated malfunction indicator lamp is a major defect on petrol cars first used from 1 July 2003 and diesels from 1 July 2008 — 371,859 failures in the DVSA data behind this site. The emissions readings are taken on a hot engine, so a car with P0316 will often sail through the gas test and still be handed a failure certificate for the lamp alone.

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

What does a P0316 code mean?: It means the engine misfired during roughly the first thousand crankshaft revolutions after a start, which is about the first half-minute of running. The control unit monitors that window separately because the catalytic converter is still cold and cannot deal with unburnt fuel, so misfires there matter more than the same misfires later. It is usually stored alongside a cylinder-specific code, and when it appears alone the misses could not be attributed to one cylinder.
Why does my car only misfire when I first start it?: Because something changes while the car stands. The three commonest are an injector that leaks fuel into a cylinder overnight and floods it, fuel pressure bleeding away through a failed check valve so the first start runs lean, and a valve that leaks when cold but seals once the cylinder head has warmed up and expanded. Worn spark plugs also fail cold before they fail warm, since a cold, rich mixture is the hardest thing to light. Note whether it happens on every start or only the first of the day, because that distinction narrows the list considerably.
Will P0316 fail an MOT if the car runs fine when it is warm?: Yes. The failure is for the lamp being illuminated, not for how the car behaves in the test bay. An illuminated engine malfunction indicator lamp is a major defect on petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, and the tester records it whatever the engine sounds like. Because the emissions readings are taken hot, cars with P0316 frequently pass the gas test and fail on the lamp alone.
Can a leaking injector cause P0316?: Yes, and it is one of the most common causes. An injector that does not seal properly drips fuel into its cylinder while the car is parked, so on the first start that cylinder is flooded and cannot fire cleanly until the excess has cleared. The tell-tale signs are a strong smell of petrol at the first start of the day, a stumble that lasts a few seconds and then vanishes, and a spark plug from that cylinder that is visibly wet when removed.

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