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P0300: Random or multiple cylinder misfire

The engine is misfiring on several cylinders or with no fixed pattern. Spark plugs, coils, air leaks or fuel supply are the usual suspects.

Code P0300 at a glance
CodeP0300
SystemEngine and transmission
GroupP03xx, Ignition and misfires
TypeGeneric: it means the same on every make
Can you keep driving?Better not

What P0300 means

The ECU detects each firing stroke through tiny changes in crankshaft speed. It has found combustion failing in more than one cylinder, or jumping from one to another. When several cylinders are affected, look first for something they all share: fuel, air or ignition.

Most common causes

  • Worn or fouled spark plugs (on petrol engines)
  • Air leak in the intake, such as a split vacuum hose or leaking gasket
  • Low fuel pressure from a blocked filter or weak pump
  • One or more faulty ignition coils
  • Poor quality or contaminated fuel
  • Dirty injectors, or low compression on several cylinders

Symptoms

  • Engine shakes and stutters
  • Engine warning light on or flashing
  • Noticeable loss of power
  • Unstable idle and higher fuel use
  • Smell of unburnt fuel from the exhaust

Can you drive with P0300?

Better not With several cylinders misfiring, a lot of unburnt fuel reaches the exhaust and can ruin the catalytic converter. If the light is flashing, stop; if it is steady, drive only as far as you need to reach a workshop.

How to check it

Many readers show a live misfire counter for each cylinder: see whether the misfires are spread evenly or concentrated on one. Also note whether the problem started right after filling up.

How to read and clear P0300 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0300 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0300 is a generic code, so it means the same on any make, for example on Abarth, Cupra, Hyundai, Jeep, Mini, Seat. See what Final OBD does on your car in makes and models.

What does code P0300 mean?

The ECU detects each firing stroke through tiny changes in crankshaft speed. It has found combustion failing in more than one cylinder, or jumping from one to another. When several cylinders are affected, look first for something they all share: fuel, air or ignition.

Can you drive with P0300?

With several cylinders misfiring, a lot of unburnt fuel reaches the exhaust and can ruin the catalytic converter. If the light is flashing, stop; if it is steady, drive only as far as you need to reach a workshop.

How do you clear P0300?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0300 comes back.