P0262
PowertrainCylinder #1 Injector Circuit High
The ECU drives each fuel injector by switching it to earth, and it watches the voltage on that circuit while it's doing it. When it sees the voltage sitting higher than it should on the cylinder 1 injector, it logs P0262. For you that usually means cylinder 1 either isn't getting fuelled properly or the wiring telling it to fire has gone faulty, and the engine will feel it.
ⓘ Information only. This page provides general educational information about fault code P0262. 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 P0262 mean?
P0262 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder #1 Injector Circuit High.
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 the first thing you notice
- • Rough, lumpy idle that smooths out a bit as revs rise
- • A clear misfire on cylinder 1, felt as a stumble or judder when pulling away
- • Down on power under load, particularly up a motorway slip road
- • Worse fuel economy than you're used to
- • In bad cases the engine drops into limp mode or stalls at junctions
Possible causes
Causes commonly associated with P0262, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Corroded or loose injector connector on cylinder 1, the most common cause. These plugs sit right in the heat and grime, and the pins corrode or the locking clip works loose
- 2. Damaged or chafed wiring between the ECU and the injector, often where the loom rubs on a bracket or the rocker cover
- 3. An open or high-resistance circuit, so the ECU sees the line floating high rather than being pulled down cleanly
- 4. Internal fault in the injector itself, with the coil resistance gone out of spec
- 5. A failed injector driver inside the ECU, which is rare but does happen on high-mileage cars
- 6. Poor earth in the injection circuit causing odd voltage readings
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 the codes and look at live data. Note the injector pulse width on cylinder 1 and whether the ECU has cut fuelling to it
- 2. Get the connector off and inspect it properly. Green corrosion on the pins, a spread terminal, or a connector full of oil will cause exactly this. Wiggle-test the loom back from the plug looking for chafe points
- 3. Measure the injector resistance with a multimeter, ignition off and connector unplugged. Most petrol injectors read roughly 12 to 16 ohms; a reading way off that or open circuit condemns the injector
- 4. Back-probe the circuit and do a voltage drop test at the ECU driver pin while the injector is commanded. A reading well above the normal switched value points at high resistance or an open in the wiring
- 5. If the injector, the wiring and the earth all check out, you're looking at the ECU driver, and that's the last thing to suspect, not the first
- 6. Check for any TSBs on your model, some makes have known connector or loom issues on this circuit
Common questions about P0262
If I clear the code, does it stay gone? +
Depends entirely on what set it. If it's a genuine wiring or injector fault, clearing it does nothing. The light comes straight back, often within a mile or two once the ECU runs that circuit again. The only time clearing it sticks is if you've already cured a loose or dirty connector and the reading was a one-off. Don't treat a code reset as a repair.
What am I risking if I just leave it? +
A dead or weak cylinder 1 dumps unburnt fuel into the exhaust, and that's the quickest way to cook a catalytic converter. A cat replacement runs into the hundreds, far more than fixing the injector circuit. You'll also be running rough, using more fuel, and you risk the engine dropping into limp mode at an awkward moment. It rarely fixes itself and tends to get worse.
How quickly do I need to sort this? +
Soon. It won't strand you the day it appears in most cases, but this isn't one to ignore for weeks. A misfiring cylinder pouring fuel through the cat is borrowing trouble. Book it in within a few days, and avoid long motorway runs under heavy load until it's looked at.
Is it the injector that's faulty or just the wiring? +
More often it's the wiring side, a corroded connector or a chafed loom, rather than the injector itself failing. That's why the connector inspection and resistance check come before condemning the injector. A new injector for cylinder 1 is the dearer fix, so prove the wiring is good first. Swapping the injector out blindly often leaves the same code if the real fault was a dodgy plug.
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 →