P0265
PowertrainCylinder #2 Injector Circuit High
The fuel injector on cylinder 2 fires a precise burst of petrol or diesel into the cylinder, and the ECM controls it by switching the injector circuit on and off. P0265 means the ECM has seen voltage on that circuit sitting high when it shouldn't be, which points to an electrical fault in the wiring, the connector, or the injector itself rather than the fuelling. The upshot is cylinder 2 isn't getting fuelled properly, so you'll feel a rough running engine and the warning light comes on.
ⓘ Information only. This page provides general educational information about fault code P0265. 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 P0265 mean?
P0265 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder #2 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 flashing if the misfire is bad enough
- • Lumpy, uneven idle that's worst when the engine is cold or sitting at a junction
- • Hesitation or a flat spot when you put your foot down
- • A noticeable misfire that stays on cylinder 2 rather than wandering around
- • Fuel economy creeping up slightly, often only a couple of percent
- • Engine running but feeling generally rough and down on power
Possible causes
Causes commonly associated with P0265, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Corroded, loose, or damaged connector at the injector. This is the first thing to suspect, especially on cars that have had engine bay work or live in damp conditions
- 2. Damaged or chafed wiring in the harness between the ECM and the injector, or a short to voltage on that control line
- 3. A faulty injector with an internal short, or coil resistance that has drifted outside spec
- 4. Water having found its way into the injector connector, which is common on engines where the loom sits low or near the bulkhead
- 5. ECM driver transistor for cylinder 2 has failed or stuck. Less common, but it does happen
- 6. A heavily contaminated injector altering how the circuit behaves, though this points more often at fuelling codes than a circuit code
- 7. ECM software or calibration fault needing a reflash, rare and usually a last resort
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 connector off the cylinder 2 injector and have a proper look. Check for green corrosion on the pins, pushed-back terminals, water sitting in the plug, or a cracked connector body. A surprising number of these are fixed right here
- 2. Measure the injector coil resistance across the terminals with a multimeter. On most petrol injectors you're looking for roughly 12 to 16 ohms; well outside that range and the injector is suspect. Diesel injectors read differently, so check the spec for your engine
- 3. Back-probe the control wire with the engine cranking and confirm you're seeing a pulsed signal, not a steady high voltage. A constant high reading tells you the circuit isn't being switched as it should
- 4. Inspect the harness from the connector back towards the ECM for rubbed-through insulation, melted sections near hot exhaust parts, or any sign of a chafe point
- 5. Swap the cylinder 2 injector with one from another cylinder and clear the code. If the fault follows the injector to the new cylinder, you've found it. If it stays on cylinder 2, you're looking at wiring or the ECM driver
- 6. If the wiring checks out and the injector is good, the ECM driver circuit is the likely culprit. Only consider the module at this stage, after everything cheaper has been ruled out
Common questions about P0265
How urgently do I need to sort this out? +
You can usually drive it, but I wouldn't leave it long. A cylinder that's misfiring is dumping unburnt fuel through the engine, and on petrol cars that fuel ends up cooking the catalytic converter, which is a far more expensive part than an injector. If the light is flashing, that's the ECM telling you the misfire is bad enough to damage the cat, so ease off and get it looked at quickly. Diesels won't kill a cat the same way but you're still running rough and risking other problems.
Is it the injector that's gone, or just the wiring and plug? +
More times than not it's the connector or the wiring, not the injector itself. Corrosion in the plug and chafed wires are cheap, common causes and worth ruling out first. The coil resistance test and the injector swap are how you tell the difference. If the fault moves when you swap the injector, the part is bad. If it stays put on cylinder 2 with a known-good injector fitted, your money's on the loom or the ECM driver.
How long does the repair take once they know what's wrong? +
A connector clean or a wiring repair is often an hour or so of labour. Replacing a single injector is usually a couple of hours, though it depends heavily on how buried the injector is and whether the bolts have seized, which is common on older engines. If it turns out to be the ECM driver, that's a bigger job involving module replacement and coding, and you're looking at the best part of a day plus the part itself.
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 →