Ignition
P0300Random/Multiple Cylinder Misfire Detected
If the check engine light is FLASHING, stop immediately: unburnt fuel can melt the catalytic converter within a few kilometres. If the light is steady, you can drive gently to the nearest workshop.
Misfiring makes the engine run unevenly and ruins exhaust emissions; a car in this condition will most likely fail inspection with a major defect.
01 / 06
What does P0300 mean?
The engine is misfiring on more than one cylinder or at random. A single bad coil usually sets a cylinder-specific code such as P0301-P0304; P0300 points to a 'shared' problem: all spark plugs are worn, the LPG tune is off, there is a vacuum leak or fuel pressure is low. If the light is flashing, don't wait, or the catalyst will go.
The ECU uses the crank sensor to monitor crankshaft acceleration on each cylinder's firing stroke. When combustion is incomplete, acceleration drops and the ECU counts it as a misfire. If misfires are not concentrated on one cylinder or are spread across several, P0300 is stored. On LPG cars, P0300 under high load (hills, overtaking) usually comes from weak coils/plugs or a lean LPG mixture.
For LPG-converted cars: LPG requires a higher ignition voltage than petrol. Worn coils and plugs misfire on LPG first. On LPG cars, halve the spark plug replacement interval.
02 / 06
How to fix P0300
Steps are ordered from cheapest to most expensive. If a step doesn't solve it, move to the next one, and don't let a garage replace parts blindly.
- 1
If the light is flashing, stop loading the engine
DIYAvoid high revs and load to protect the catalyst; if possible, have it towed or drive only a short distance to a workshop.
- 2
Read the misfire counters
DIYCheck the per-cylinder misfire counters in OBD live data. If misfires are concentrated on one cylinder, the problem is specific to that cylinder.
- 3
Inspect / replace the spark plugs
DIYA widened gap, cracked porcelain or sooty plug is the most common cause. Plug life is halved on LPG; use the type and gap specified by the manufacturer.
- 4
Coil swap test
DIYMove the suspect cylinder's coil to another cylinder; if the misfire follows it, the coil is faulty.
- 5
Vacuum leak and LPG tune
Pro jobIf it only misfires on LPG, have the LPG injectors, filter and map checked.
- 6
Compression test
Pro jobIf misfires continue with new plugs and coils, measure compression. A low cylinder points to a valve or piston ring problem.
- 7
Valve adjustment / cylinder head
Pro jobThe last stop on LPG engines whose valve adjustment has been neglected. Cylinder head machining is expensive.
Don't replace these first
- Engine control unit (ECU)
- Crankshaft position sensor
- Catalytic converter
These parts are often replaced unnecessarily for P0300. Don't spend money on them before doing the checks above.
03 / 06
P0300 symptoms
- Check engine light on or flashing
- Engine runs roughly, shaking at idle
- Loss of power and 'stumbling' when accelerating
- Petrol smell from the exhaust
- Fuel consumption goes up
- Misfiring uphill on LPG
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What causes P0300?
- Worn-out spark plugs (especially on LPG cars)Very high
- Weak ignition coil / plug leadsHigh
- LPG mixture or injector problemHigh
- Vacuum leakMedium
- Low fuel pressure / dirty injectorsMedium
- Incorrect valve clearance or burnt valve (low compression)Low
- Crank / cam sensor signal problemLow
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Which cars commonly get P0300?
- BMW 3 Serisi 320iN20B20
- Chevrolet Cruze 1.6 EcotecF16D4
- Citroen C3 1.2 PureTech 110EB2DT (1.2 PureTech)
- Dacia Duster 1 1.6 16V 105K4M
- Dacia Sandero 2 1.2 16V 75D4F
- Fiat Egea 1.4 Fire 951.4 Fire 16V
- Fiat Linea 1.4 Fire 771.4 Fire 8V
- Ford Focus 3 1.6 Ti-VCT 125Sigma 1.6 Ti-VCT
- Honda Civic 1.6 i-VTECR16B
- Honda Civic 1.6 i-VTEC EcoR16B
- Mercedes-Benz C Serisi C180M274 (1.6 turbo)
- Opel Astra J 1.6 TwinportA16XER
- Opel Corsa D 1.2 TwinportZ12XEP
- Peugeot 2008 1.2 PureTech 110EB2DT (1.2 PureTech)
- Peugeot 208 1.2 PureTech 110EB2DT (1.2 PureTech)
- Peugeot 3008 II 1.2 PureTech 130EB2DTS (1.2 PureTech)
- Renault Captur 1 1.2 TCe 120 EDCH5Ft (1.2 TCe)
- Renault Clio 4 1.2 16V 75D4F
- Renault Clio 4 1.2 TCe 120 EDCH5Ft (1.2 TCe)
- Renault Fluence 1.6 16VK4M
- Renault Megane 4 1.2 TCe 130H5Ft (1.2 TCe)
- Renault Megane 3 1.6 16V 110K4M
- Renault Symbol 1.2 16V 75D4F
- Skoda Octavia 3 1.4 TSI 150EA211 1.4 TSI
- Toyota Auris 1.6 Valvematic1ZR-FAE
- Toyota C-HR 1.8 Hybrid2ZR-FXE
- Toyota Corolla 1.6 Valvematic1ZR-FAE
- Toyota Corolla 1.8 Hybrid2ZR-FXE
- Volkswagen Golf 7 1.4 TSI 125EA211 1.4 TSI
- Volkswagen Jetta 6 1.4 TSI 125EA211 1.4 TSI
- Volkswagen Passat B8 1.4 TSI 150EA211 1.4 TSI
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Frequently asked questions
What does fault code P0300 mean?
P0300 stands for “Random/Multiple Cylinder Misfire Detected”. The engine is misfiring on more than one cylinder or at random. A single bad coil usually sets a cylinder-specific code such as P0301-P0304; P0300 points to a 'shared' problem: all spark plugs are worn, the LPG tune is off, there is a vacuum leak or fuel pressure is low. If the light is flashing, don't wait, or the catalyst will go.
Can I drive with code P0300?
No, stop driving. If the check engine light is FLASHING, stop immediately: unburnt fuel can melt the catalytic converter within a few kilometres. If the light is steady, you can drive gently to the nearest workshop.
Will a car with code P0300 pass vehicle inspection?
Likely to fail. Misfiring makes the engine run unevenly and ruins exhaust emissions; a car in this condition will most likely fail inspection with a major defect.
What is the difference between P0300 and P0301?
P0301 says there is a misfire on cylinder 1 only; P0300 means misfires are random or on more than one cylinder. P0300 usually points to a common problem affecting all cylinders.
The check engine light is flashing. What should I do?
This signals a serious misfire. Unburnt fuel reaches the catalyst and overheats it. Stop as soon as possible without loading the engine and take the car to a workshop.