P0286
Cylinder 9 Injector Circuit HighP0286 is a generic OBD-II powertrain diagnostic trouble code: Cylinder 9 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.
What P0286 means
P0286 is triggered when the PCM/ECM measures a voltage or current level above the calibrated maximum on the cylinder 9 fuel injector driver circuit. Unlike the low-circuit fault (P0285) which typically points to open wiring or high resistance, a high-circuit condition suggests the signal line is being pulled up toward battery voltage by a short to power, a shorted injector coil winding, or a failed PCM output driver that can no longer control the low-side of the circuit.
This code only appears on engines with nine or more cylinders. Vehicles most commonly affected include the BMW S85 V10 (M5/M6), Dodge Viper V10, Ford 6.8 L Triton V10 (F-250/F-350 Super Duty and Excursion), Lamborghini Gallardo and Huracán V10, Audi R8 V10, and various V12 applications. The extended wiring runs on these large engine bays increase the risk of insulation damage that allows conductor-to-power shorts.
A shorted injector coil is one of the most frequent hardware culprits, as the internal winding can fail internally between the two terminals or externally short to the injector body. Ethanol-blended fuels have been documented to accelerate internal injector wear, which can eventually cause winding insulation breakdown. Regardless of the root cause, the affected cylinder will not fire correctly, leading to a misfire, rough running, and potential catalyst damage if the condition persists.
Common causes
Most-frequently reported root causes when P0286 is logged.
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1
Shorted fuel injector coil winding on cylinder 9, creating a low-impedance path that raises circuit current above threshold.
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2
Wiring harness short to battery voltage between the PCM driver pin and the cylinder 9 injector connector.
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3
Corroded or moisture-contaminated injector connector forcing abnormal voltage on the signal wire.
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4
Failed PCM/ECM low-side driver transistor for cylinder 9 that can no longer pull the circuit low.
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5
Damaged wiring insulation allowing the injector control wire to contact a 12 V supply rail.
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6
Ethanol-related injector wear causing internal winding insulation breakdown and inter-winding short.
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7
Aftermarket wiring modification or improper splice introducing unwanted voltage into the injector circuit.
Symptoms drivers notice
How to diagnose P0286
A typical diagnostic flow when this code is present.
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1
Retrieve all stored DTCs and freeze-frame data with an OBD-II scan tool before clearing codes.
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2
Visually inspect the cylinder 9 injector wiring harness for chafed insulation, pinched wires, or any contact with a power rail or hot component.
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3
Disconnect the cylinder 9 injector connector and measure coil resistance at the injector body; a reading significantly below specification (or near zero) confirms an internally shorted coil.
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4
With the injector disconnected and ignition on, probe the harness-side driver wire for unexpected high voltage; anything above 1 V with the driver commanded off indicates a short to power.
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5
Check the injector connector and wiring continuity back to the PCM, looking for any inadvertent contact with B+ lines in the harness loom.
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6
Perform a fuel injector balance test (if supported by the scan tool) to quantify cylinder 9 fuel delivery versus the other cylinders.
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7
If all external components test within spec, suspect the PCM internal driver for cylinder 9 and compare software version against current manufacturer TSBs before authorising module replacement.
Related powertrain codes
- P0065 — Air Assisted Injector Control Range/Performance
- P0066 — Air Assisted Injector Control Circuit or Circuit Low
- P0067 — Air Assisted Injector Control Circuit High
- P0087 — Fuel Rail/System Pressure - Too Low
- P0088 — Fuel Rail/System Pressure - Too High
- P0089 — Fuel Pressure Regulator 1 Performance
Frequently asked questions
Which vehicles are affected by P0286?
Only multi-cylinder engines with nine or more cylinders can produce this code. Common platforms include the BMW S85 V10, Dodge Viper V10, Ford 6.8 L Triton V10, Lamborghini Gallardo/Huracán V10, Audi R8 V10, and V12 engines.
How does P0286 differ from P0285?
P0285 (Circuit Low) means the injector circuit voltage or current is below the PCM's minimum limit, typically from an open or high-resistance path. P0286 (Circuit High) means it is above the maximum limit, typically from a short to voltage or a shorted injector winding.
Can ethanol fuel cause P0286?
Ethanol-blended fuels, particularly E10, introduce water vapour that can degrade injector winding insulation over time. This internal wear can eventually cause an inter-winding short that raises circuit impedance anomalies and triggers the high-circuit code.
Do I need to replace the PCM if P0286 is set?
Not necessarily. The most common causes are an externally shorted injector coil or wiring fault, both of which are less expensive to fix than a PCM. Thoroughly test the injector and harness before considering module replacement.
Disabling P0286 in software
RaceTune can permanently disable P0286 — 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.
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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