What causes fault code P0286?

• Most likely: Short to voltage in the wiring harness for injector 9 • Likely: Faulty fuel injector (internal solenoid short) • Possible: Corrosion or damaged pins in the injector connector • Rare: Internal PCM/ECU driver failure

Powertrain (Engine & Gearbox)Standard EOBD

P0286 - Cylinder 9 Injector Circuit High

Q: What are the symptoms of fault code P0286?

• Check engine light (MIL) illumination • Engine misfiring, especially under load • Rough idling and reduced engine power • Increased fuel consumption • Vehicle may enter 'Limp mode'

Q: How do you fix fault code P0286?

STEP 1: Inspect the connector at injector 9 for corrosion, moisture, or backed-out pins. STEP 2: Use a multimeter to check the internal resistance of the injector. It should typically be between 12-16 Ohms. Replace if it shows signs of a short. STEP 3: Check the wiring harness for a short to voltage. With the key on and engine off, ensure the ground-side wire is not showing battery voltage when it should be floating or grounded by the ECU pulse. STEP 4: Test with a Noid light or oscilloscope to verify the pulse width modulation (PWM) from the PCM. If the PCM driver is stuck high, the unit may need replacement or repair.

Last updated:1 February 2026

Related:Fuel Injector, Engine Control Unit (ECU), Wiring Harness, Spark Plug

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0200

Injector Circuit Malfunction

P0201

Cylinder 1 Injector Circuit Open

P0202

Injector Circuit - Cylinder 2 - Malfunction

P0203

Injector Circuit - Cylinder 3

Technical Description

P0286 is a generic OBD-II diagnostic trouble code indicating that the Engine Control Unit (ECU/PCM) has detected a voltage level within the cylinder 9 injector circuit that is higher than the manufacturer's calibrated limit. The ECU monitors the feedback voltage from the fuel injector driver. If the voltage stays high when it should be low (pulled to ground), it signifies a potential short to voltage in the wiring harness or an internal fault in the injector solenoid. This fault will typically trigger a misfire and may cause the ECU to enter a fail-safe mode where the specific injector is disabled to prevent catalytic converter damage.

Possible Causes

Short to voltage in the wiring harness for injector 9

Faulty fuel injector (internal solenoid short)

Corrosion or damaged pins in the injector connector

Internal PCM/ECU driver failure

Symptoms

Check engine light (MIL) illumination

Engine misfiring, especially under load

Rough idling and reduced engine power

Increased fuel consumption

Vehicle may enter 'Limp mode'

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P0286 - Cylinder 9 Injector Circuit High

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P0286 - Cylinder 9 Injector Circuit High

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