P0363
PowertrainMisfire Detected - Fueling Disabled
You'll feel the car shaking at idle, then it'll buck and hesitate when you try to pull away, often with the engine light flashing at you. What's happening underneath is that the ECU has spotted a misfire bad enough that it's switched off the fuel to that cylinder on purpose. It does this to stop raw petrol pouring into the cat and cooking it. So P0363 isn't really a fault on its own, it's the car's reaction to a misfire that's already there, and your job is to find out which cylinder is dropping out and why.
ⓘ Information only. This page provides general educational information about fault code P0363. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0363 mean?
P0363 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Misfire Detected - Fueling Disabled.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light flashing rather than steady, which means an active misfire that's damaging the cat right now
- • Rough, lumpy idle that you can feel through the seat and the steering wheel
- • The car stumbling or jerking when you accelerate, especially uphill or under load
- • Down on power, sometimes feels gutless and will struggle to get above motorway speeds
- • A smell of unburnt petrol from the back of the car
- • Higher fuel use, because the engine is working harder on fewer cylinders
Possible causes
Causes commonly associated with P0363, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Worn spark plugs, the cheapest and most common cause. If they haven't been changed in 40,000 miles or more, start there
- 2. Failed ignition coil. Coil-on-plug setups are everywhere now and they do fail one at a time, which is why the misfire often sits on a single cylinder
- 3. Cracked or perished plug leads or coil boots on older cars, letting the spark track to earth instead of jumping the gap
- 4. Vacuum leak letting in unmetered air, often a split intake hose or a perished breather pipe, which leans out the mixture and triggers misfires
- 5. A blocked or sticking fuel injector that isn't delivering a proper spray on that cylinder
- 6. Low fuel pressure from a tired pump or a duff pressure regulator, which tends to misfire across several cylinders at once
- 7. Poor connection or chafed wiring in the ignition circuit, worth a look if the misfire comes and goes
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read the codes and see what else is stored alongside it. A cylinder-specific code like P0301 to P0312 tells you exactly which pot to look at, which saves you guessing
- 2. Pull the spark plugs and read them. Look for fouling, a wide gap, oil in the wells, or a cracked porcelain. A knackered plug is your quickest win
- 3. Swap the coil from the misfiring cylinder to a good one and clear the codes. If the misfire moves with the coil, you've found it
- 4. Check the intake and breather hoses for splits and loose clips. A smoke test makes a small vacuum leak obvious if the visual check doesn't
- 5. Confirm fuel pressure against the manual figures and look at the injector on the dead cylinder. A weak pump or a gummed-up injector will show here
- 6. If plugs, coils, air and fuel all check out, look harder at the wiring and connectors to that cylinder before condemning anything expensive
Common questions about P0363
Can I carry on driving or should I stop? +
If that engine light is flashing, keep your foot off it and get it home or to a garage gently. A flashing light means the cat is being hammered by a live misfire, and a new catalytic converter is the last thing you want to pay for. Cruising it the odd mile to the garage won't kill it, but using it as your daily while it stumbles and shakes is asking for a much bigger bill.
Is this going to cause an MOT fail? +
The code by itself isn't a direct fail, but if the engine warning light is lit when the tester plugs in or eyeballs the dash, that's an automatic emissions-related fail under current rules. A flashing light makes it worse because the examiner can see there's an active misfire. Sort the cause, clear the light, drive a few cycles to make sure it stays off, then book the test.
What sort of money am I looking at to fix it? +
Depends entirely on what's dropping the cylinder. A set of plugs fitted at an independent is often under £100. A single ignition coil might be £80 to £200 fitted, a full set more. Chasing a vacuum leak or a fuel injector problem can climb into the £300 to £500 range once diagnosis time is added, and a main dealer will typically charge a fair bit more on labour for the same work. Get the cause diagnosed first so you're not throwing parts at it.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →