P0262

Cylinder 1 Injector Circuit High

P0262 is a generic OBD-II powertrain diagnostic trouble code: Cylinder 1 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
P0262
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
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What P0262 means

P0262 is stored when the ECM/PCM detects a higher-than-expected voltage in the cylinder 1 fuel injector control circuit. The ECM drives the injector by pulling the control wire low through an internal transistor. A circuit-high fault means the control wire is being held near supply voltage (12 V) instead of being pulled to ground during the drive pulse — indicating the driver transistor cannot ground the circuit, typically because of a short to the supply voltage somewhere in the wiring or a failure of the driver itself.

Unlike the circuit-low fault (P0261), a short to voltage forces the injector control line high regardless of what the ECM commands. The injector may remain partially energised or the ECM may detect the conflict and shut down that driver channel entirely to protect itself. Either way, cylinder 1 does not receive a normal injector pulse, producing misfire and rough running behaviour similar in feel to P0261 but with a different electrical signature.

Common root causes are a chafed harness wire contacting a 12 V source, a damaged injector connector with internal pin bridging, or a shorted injector that back-feeds voltage through the winding. ECM driver failure is uncommon but possible when short-to-voltage events have occurred repeatedly without repair.

Common causes

Most-frequently reported root causes when P0262 is logged.

  • 1
    Short to supply voltage (12 V) in the cylinder 1 injector control wire, caused by harness chafing against a power feed
  • 2
    Damaged injector connector with internal bridging between the control pin and the power supply pin
  • 3
    Injector coil winding internally shorted to the power supply rail
  • 4
    Failed ECM/PCM injector driver transistor for cylinder 1, unable to pull the circuit low (rare)
  • 5
    Incorrect aftermarket wiring or splice introducing unwanted voltage on the control line
  • 6
    Water or coolant intrusion into the harness connector creating a conductive path to 12 V

Symptoms drivers notice

Check engine light illuminated, often alongside P0301 (cylinder 1 misfire)
Rough idle or misfire on cylinder 1 due to abnormal or absent injector drive pulse
Reduced engine power and hesitation under acceleration
Possible smell of unburnt fuel if the injector is partially held open by the circuit fault
Engine may enter limp mode on vehicles with active misfire protection strategies

How to diagnose P0262

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all DTCs and freeze-frame data; note whether P0301 or the companion low-circuit code P0261 are also present.
  2. 2
    Visually inspect the cylinder 1 injector harness from the connector to the ECM for any chafing, pinching, or contact with hot engine components or power wires.
  3. 3
    With the ignition on and the injector disconnected, measure voltage on the control wire at the harness side — normal is 0 V with the ECM not commanding; a reading near 12 V confirms a short to supply.
  4. 4
    Inspect the injector connector for bent or bridged pins and for moisture or corrosion that could create a conductive path.
  5. 5
    Measure injector coil resistance; an unusually low reading indicates an internal winding short that could back-feed voltage.
  6. 6
    Isolate the harness section carrying the fault by disconnecting intermediate connectors and repeating the voltage measurement to locate the exact short.
  7. 7
    Repair the harness short before replacing any ECM component; if the short has persisted long enough to damage the driver, verify ECM driver function with a known-good injector after harness repair.

Related powertrain codes

Frequently asked questions

What is the difference between P0261 (circuit low) and P0262 (circuit high)?

P0261 means the injector control line is at a lower voltage than expected — pointing to an open circuit, ground short, or high-resistance fault. P0262 means the line is at a higher voltage than expected — pointing to a short to 12 V supply voltage. The two codes indicate opposite electrical failure modes and require different diagnostic approaches.

Can P0262 damage the ECM?

Yes, potentially. A persistent short-to-voltage on the injector control line can stress or destroy the ECM's injector driver transistor. Repairing the wiring fault before clearing the code and retesting is important; if the short is left in place and the car is repeatedly started, the driver IC may eventually fail, requiring ECM repair or replacement.

Will the engine still run with P0262 set?

Usually yes, but roughly. Many ECMs detect the high-voltage conflict on the driver channel and disable that channel to protect hardware, effectively cutting cylinder 1 entirely. The engine runs on the remaining cylinders with a noticeable misfire. In some strategies the channel remains active and delivers distorted pulses.

Is P0262 common on any specific engine family?

Circuit-high injector faults are reported across many platforms but are frequently seen on engines where the injector harness routes near the exhaust manifold — heat over time degrades insulation and creates shorts to nearby power wires. Vehicles with known injector harness routing issues include some Ford EcoBoost and GM GDI engines, though the code itself is manufacturer-agnostic.

Disabling P0262 in software

RaceTune can permanently disable P0262 — 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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