P0265

Cylinder 2 Injector Circuit High

P0265 is a generic OBD-II powertrain diagnostic trouble code: Cylinder 2 Injector Circuit High. It is logged by the engine control unit when the fuel/inj monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0265
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
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What P0265 means

P0265 is stored when the engine control module (ECM) detects that the voltage on the cylinder 2 fuel injector control circuit is higher than expected. The ECM operates each injector by grounding its control line through an internal driver transistor; when the transistor switches on, voltage collapses to near zero and the injector opens. If the measured voltage remains elevated instead of pulling low, the ECM logs P0265 and illuminates the MIL.

The most common hardware root causes are a wiring short to battery voltage somewhere between the ECM and the cylinder 2 injector connector, or an internal short inside the injector solenoid coil itself that raises its resistance above the normal 12–16 Ω range on high-impedance injectors (or below 0.5–2 Ω on peak-and-hold types), confusing the driver circuit. A failed ECM output transistor that is stuck in the energised state can produce the same symptom even with good external wiring.

Cylinder 2 will typically mis-fire or receive uncontrolled fuel delivery while this fault is active, causing rough idle, reduced power, and elevated fuel consumption. Continuing to drive with an active injector circuit fault risks unburnt fuel entering the exhaust stream and overheating the catalytic converter, so the fault should be diagnosed promptly.

Common causes

Most-frequently reported root causes when P0265 is logged.

  • 1
    Short circuit to battery voltage in the wiring harness between the ECM and the cylinder 2 injector connector.
  • 2
    Corroded, spread, or backed-out terminals at the cylinder 2 injector electrical connector causing high-resistance contact.
  • 3
    Internal injector solenoid winding failure — shorted turns alter coil resistance outside the ECM driver's expected range.
  • 4
    Failed ECM injector driver transistor stuck in the on (energised) state, holding the control line high regardless of command.
  • 5
    Chafed or pinched injector harness wire making intermittent contact with another voltage-carrying circuit.
  • 6
    Water or oil intrusion into the injector connector causing leakage current that raises the measured circuit voltage.
  • 7
    Incorrect injector fitted (wrong impedance type) that behaves abnormally under the ECM's peak-and-hold or saturated drive strategy.

Symptoms drivers notice

MIL (check engine light) illuminated, with P0265 stored; a flashing MIL indicates an active misfire on cylinder 2.
Rough or uneven idle caused by cylinder 2 firing incorrectly or not at all.
Hesitation or stumble during acceleration, most noticeable at low engine speeds.
Noticeable power loss, particularly under load, when cylinder 2 is not contributing normally.
Increased fuel consumption (typically 2–4%) due to incomplete combustion or ECM fuel-trim compensation.
Possible catalytic converter overheating if raw fuel exits cylinder 2 unburnt.

How to diagnose P0265

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool, retrieve all stored DTCs and freeze-frame data, and note any companion misfire codes (e.g. P0302) that confirm cylinder 2 is affected.
  2. 2
    Visually inspect the cylinder 2 injector connector and harness for chafing, melted insulation, corrosion, or spread pins; repair any obvious damage before proceeding.
  3. 3
    With the injector connector unplugged and ignition off, measure solenoid resistance across the injector terminals — compare against the OEM specification (typically 12–16 Ω saturated or 0.5–2 Ω peak-and-hold); replace the injector if out of range.
  4. 4
    With the injector connector unplugged and ignition on (engine off), backprobe the harness control wire and measure voltage to ground — it should be near battery voltage on the supply side; any elevated voltage on the ECM driver wire indicates a short to power in the harness.
  5. 5
    Use a lab-scope or injector pulse tester on the ECM driver line while cranking to confirm the ECM is sending a proper switching signal; a line that never pulls low suggests an internal ECM driver fault.
  6. 6
    Swap the cylinder 2 injector with a known-good injector from another cylinder; if the fault follows the injector to its new location the injector is faulty, if it stays on cylinder 2 the fault is in the wiring or ECM.
  7. 7
    After all repairs, clear codes, run a drive cycle that includes idle and load conditions, and rescan to confirm no return of P0265.

Related powertrain codes

Frequently asked questions

What is the difference between P0265 (circuit high) and P0264 (circuit low) for cylinder 2?

P0264 means the injector control line is being pulled to ground when it should not be — typically an open circuit or short to ground. P0265 is the opposite: the line stays at elevated voltage rather than pulling low when the ECM fires the driver, pointing to a short to battery voltage or a failed ECM driver transistor stuck on.

Can P0265 trigger a cylinder 2 misfire code (P0302) at the same time?

Yes. When the injector circuit fault prevents normal fuel delivery to cylinder 2, combustion events are irregular and the ECM's misfire monitor counts misfires on that cylinder. Expect P0302 alongside P0265 in many cases; fixing the injector circuit fault will usually resolve the misfire code as well.

Is it safe to drive with P0265 stored?

Short distances to reach a workshop are generally acceptable if the MIL is steady, but a flashing MIL indicates an active severe misfire that can quickly overheat and destroy the catalytic converter. Extended driving is not recommended regardless, as uncontrolled fuel delivery on cylinder 2 also risks hydrolock or bore wash.

How do I tell whether the fault is in the wiring or the injector itself?

Measure injector solenoid resistance first — if it is out of specification the injector is the likely culprit. If resistance is correct, backprobe the harness control wire with the connector unplugged to check for unwanted voltage, and confirm with a lab-scope that the ECM driver line actually switches during cranking. Swapping the injector to another cylinder is the definitive isolation test.

Disabling P0265 in software

RaceTune can permanently disable P0265 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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