P0263
PowertrainCylinder 1 Contribution/Balance Fault
This can go either way on cost, anywhere from a cheap spark plug to a stripped-down engine, so don't panic but don't ignore it either. What the ECU is telling you is that cylinder 1 isn't pulling its weight during combustion. It works out roughly how much each cylinder is contributing from the way the crankshaft speeds up and slows down on each firing stroke, and when number 1 falls short, it flags this. Most of the time the culprit is fuelling or ignition on that one cylinder, and those are the jobs that don't hurt the wallet. The compression-related causes are the expensive end.
ⓘ Information only. This page provides general educational information about fault code P0263. 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 P0263 mean?
P0263 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 1 Contribution/Balance Fault.
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 on, sometimes flashing if the misfire is bad enough to threaten the cat
- • Lumpy, shaky idle that you can feel through the seat or steering wheel when stopped at lights
- • Flat spot and hesitation when you put your foot down
- • An audible misfire, often a stutter or a popping note that comes and goes
- • Petrol smell at the back of the car from unburnt fuel going out the exhaust
- • Worse fuel economy and a general lack of smoothness at a steady motorway cruise
Possible causes
Causes commonly associated with P0263, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Dirty or sticking fuel injector on cylinder 1, the most common cause. The injector isn't delivering its full dose so the cylinder runs weak
- 2. Fouled spark plug or a tired ignition coil on cylinder 1, weak spark means a weak burn
- 3. Damaged, chafed or corroded wiring to the cylinder 1 injector, or a dodgy connector with green pins. The signal gets there but not cleanly
- 4. Low compression in cylinder 1 from worn rings, a burnt valve or a head gasket issue. This is the costly one to find at the bottom of the list
- 5. A vacuum leak feeding extra air into that one cylinder and leaning it out
- 6. Less often, a fault in the injector driver inside the ECM itself, or the module needing a software update
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. Pull all the codes, not just this one. If you've got a P0301 misfire or a P0201 injector circuit code sitting alongside it, that points you straight at the cause and saves you guessing
- 2. Get the inlet manifold cover off and inspect the injector wiring and connector on cylinder 1. Look for chafed insulation, corroded pins and a connector that isn't clicked home properly. This is five minutes and catches a fair few of them
- 3. Read the per-cylinder fuel trim and injector pulse width in live data and compare cylinder 1 to the others. If the ECU is piling extra fuel into number 1 to keep up, the injector or compression is the issue
- 4. Swap the cylinder 1 coil and plug with a neighbour, clear the code and drive it. If the fault jumps to the other cylinder, you've found a cheap fix without buying anything
- 5. If fuelling and ignition check out, do a compression test on cylinder 1. A reading well down on the others tells you the problem is mechanical and the bill just went up
Common questions about P0263
Will my car get through its MOT with this stored? +
The MOT tester isn't plugging in a code reader, so P0263 sitting in memory won't fail you on its own. What gets you is the engine warning light being lit when the car goes in for its test, since an illuminated MIL is a fail on most cars from 2018 onwards. If the cylinder really is dead it'll also show up on the emissions probe, because a misfiring pot dumps unburnt hydrocarbons. Fix the cause, clear the light and drive a few cycles so it stays off before you book it in.
What's it likely to cost me to sort out? +
Depends entirely on which of the causes it turns out to be. A spark plug is small change and an ignition coil is usually £30 to £90 for the part plus an hour's labour at an independent. A new injector for cylinder 1 sits roughly in the £100 to £300 fitted range at a good local garage, more on some direct-injection engines. If a compression test shows worn rings or a burnt valve, you're into proper engine work and that can run well into four figures. A main dealer will charge noticeably more on labour and diagnostic time than an independent for the exact same repair, so for an out-of-warranty car the indy is the sensible call.
How do I work out which of these it actually is on my car? +
Let the cheap-to-swap parts tell you. Move the cylinder 1 coil and plug to another cylinder, clear the code and see if the fault moves with them. If it does, you've found it for the price of nothing. If the fault stays put on cylinder 1, you're looking at the injector or the wiring to it, so check the connector and harness next. Only when ignition, fuelling and wiring all come back clean should you do a compression test, because that's the one that confirms the expensive mechanical answer.
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 →