P0202
PowertrainCylinder 2 Injector Circuit Malfunction
The ECU has spotted an electrical fault in the wiring or driver circuit that fires the fuel injector on cylinder 2. The injector is either not getting the right signal to open and close, or the ECU can't see the circuit behaving the way it should. For you that usually means a rough-running engine and a warning light, and the cause sits somewhere between the connector, the loom, and the injector itself rather than the mechanical fuel side.
ⓘ Information only. This page provides general educational information about fault code P0202. 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 P0202 mean?
P0202 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 2 Injector Circuit Malfunction.
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 management light on, sometimes flashing if cylinder 2 is actively misfiring
- • Rough, lumpy idle that you can feel through the steering wheel and gear stick at a standstill
- • Hesitation or a flat spot when you put your foot down, especially pulling away or overtaking
- • Noticeably down on power, the car feels like it's running on one less cylinder because it often is
- • Harder starting or longer cranking, particularly first thing on a cold morning
- • Heavier fuel use and sometimes a raw petrol smell from the exhaust
Possible causes
Causes commonly associated with P0202, 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 2. This is the first thing to suspect, especially on older cars where the plastic clip has gone brittle and the terminals have tarnished
- 2. Chafed or broken wiring in the injector harness. Heat and engine vibration eventually wear through the insulation, and oil contamination from a weeping cam cover gasket doesn't help
- 3. Open or short circuit in the injector control wire, which the ECU reads as the circuit being dead or shorted to earth
- 4. Faulty injector with an internal coil failure. The winding goes open or shorts internally and the resistance falls outside spec
- 5. Poor earth or supply voltage feeding the injector, often traced back to a corroded earth point on the engine block
- 6. Failed injector driver inside the ECU itself. Rare, but it does happen, and it's the most expensive ending to this one
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. Unplug the cylinder 2 injector connector and look hard at it. Bent or pushed-back pins, green corrosion, oil in the connector, and a cracked locking clip all turn up here regularly and cost nothing to find
- 2. Scan for company. P0202 rarely travels alone, so check for P0302 misfire on the same cylinder and any general P0200 or mixture codes that point you toward wiring versus injector
- 3. Measure the injector resistance across its two pins with a multimeter and compare to your service data. Most petrol injectors land somewhere around 12 to 16 ohms, but check the figure for your engine before you condemn anything
- 4. Back-probe the connector for voltage with the ignition on and during cranking, and confirm you've got a clean earth path. A reading well under 10 volts points at supply or earth trouble rather than the injector
- 5. Swap the cylinder 2 injector with a known-good one from another cylinder and clear the code. If the fault follows the injector to its new home, the injector's the problem. If P0202 stays put on cylinder 2, you're looking at wiring or the ECU driver
Common questions about P0202
What happens if I just keep driving with it like this? +
You can limp it home, but don't make a habit of it. With cylinder 2 misfiring, raw unburnt petrol gets dumped down the exhaust and cooks the catalytic converter, and a cat is a far dearer fix than an injector or a bit of wiring. You'll also be wasting fuel and risking the car dropping into limp mode on the motorway. Short hops to get to a garage are fine. Daily driving for weeks while you ignore it is asking for a bigger bill.
How quickly do I actually need to sort this? +
Treat it as a this-week job, not a tomorrow-morning emergency, unless the warning light is flashing. A flashing light means a live misfire that's actively damaging the cat, and that one you deal with straight away. A steady light with a slightly rough idle gives you a bit of breathing room, but the longer the engine runs lean or misfiring, the more chance you do collateral damage to the cat or foul the spark plug on that cylinder.
Is it the injector that's gone, or just the wiring to it? +
More often it's the connection rather than the injector. Connectors corrode, locking clips break, and the loom chafes where it rubs on the engine. The injector swap test settles it cleanly: move the suspect injector to another cylinder, and if the code follows it, the injector's faulty. If P0202 stays on cylinder 2 after the swap, the injector is innocent and your fault lives in the wiring, the earth, or the ECU driver. Always rule out the cheap stuff before buying an injector.
How long is this in the garage for? +
A wiring or connector repair is usually an hour or two of diagnosis and fixing, so you might get the car back the same day. Replacing a single injector is typically a couple of hours of labour depending on how buried it is, and on some engines you're paying more for access than for the part. If the trail leads to the ECU driver circuit, expect longer while they confirm it and either repair, reprogram, or swap the unit, and that's the job that can stretch into days if a coded replacement ECU has to come in.
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 →