P0268
PowertrainCylinder #3 Injector Circuit High
Most of the time this is a smaller job than people fear. The ECU has seen too much voltage on the wiring that fires the cylinder 3 injector, which usually points at a dodgy connector or a chafed wire rather than a dead engine. The injector itself can be at fault, and now and then the control module is to blame, but you chase the cheap stuff first. Get it diagnosed properly before anyone talks you into a new injector.
ⓘ Information only. This page provides general educational information about fault code P0268. 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 P0268 mean?
P0268 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder #3 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:
- • Rough, lumpy idle that you can feel through the seat
- • A misfire you notice on pull-away, often a stumble or buck under light throttle
- • Engine warning light on, sometimes flashing if the misfire is bad
- • Down on power, sluggish when you put your foot down
- • Fuel economy creeping up because cylinder 3 isn't pulling its weight
- • Stalling or hesitation, and in worse cases the car drops into limp mode
Possible causes
Causes commonly associated with P0268, 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 connector at the cylinder 3 injector. This is where I'd put my money first, especially on cars that live outside
- 2. Chafed or rubbed-through wiring in the injector harness, often where it runs near hot or moving parts
- 3. A short to voltage somewhere in the circuit between the injector and the ECU, which is exactly what 'high' in the code description is hinting at
- 4. The injector itself failed internally, either open or shorted
- 5. Water ingress into the connector or loom, leading to corrosion and false readings
- 6. Less common but real: a faulty ECU or, on certain diesels with a separate FICM, a failed injector control module
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. Plug in a scanner and read the freeze frame data so you know when it set, then clear it and drive to see if it comes straight back or is intermittent
- 2. Unplug the cylinder 3 injector connector and look hard at it. Green crust, bent pins, a loose terminal or damp inside is your answer most of the time. Clean it up and add a touch of dielectric grease
- 3. Follow the loom by hand and eye, checking for chafing or melted insulation where it passes anything hot or sharp
- 4. With the injector unplugged, put an ohmmeter across its terminals. Petrol injectors usually read in the low ohms, often around 12 to 16 ohms, while some diesel units sit much lower. Anything wildly off, or open circuit, condemns the injector
- 5. Check the harness for a short to battery voltage or to ground with a multimeter, which is what causes the 'high' reading
- 6. Only when the wiring and injector check out should you look at the ECU or, where fitted, the separate injector driver module
Common questions about P0268
If it's the injector, do I need a genuine one or will a cheaper aftermarket do? +
For a single injector replacement a quality aftermarket or remanufactured unit from a known brand like Bosch, Delphi or Denso is fine and will save you a fair bit over main dealer pricing. What I'd steer clear of is the £20 eBay no-name stuff, especially on common rail diesels where the spray pattern and electrical characteristics need to match the others. On diesels in particular, mismatched injectors can leave the engine running rough even with no fault code, so buy from a reputable supplier.
Can I keep driving with P0268 showing? +
You can limp it home or to the garage, but I wouldn't run around on it for weeks. A cylinder dropping out means unburnt fuel washing past, and on petrol cars a persistent misfire can cook your catalytic converter, which turns a cheap fix into an expensive one. If it's stumbling badly or dropping into limp mode, get it looked at quickly rather than risking a stall in traffic.
Is this going to fail the MOT? +
The code on its own isn't tested, but the engine warning light is. If the MIL is lit when the tester checks it, that's a major defect and a fail under current rules. Sort the fault, clear the light and drive a few miles so the readiness monitors complete before you book it in. A genuine misfire can also push your emissions out, which is another way to fall foul of the test.
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 →