P0287

Cylinder 9 Injector Circuit High

Powertrain Fuel and Air Metering Fuel injector circuit 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

The engine computer detected that cylinder 9's fuel injector is receiving too much electrical voltage, similar to a light switch stuck in the on position. This prevents proper fuel delivery and causes the engine to run rough or misfire.

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Symptoms You May Notice

3 known symptoms for this code
Rough idle or engine misfire on cylinder 9
Reduced fuel economy and loss of power
Check Engine Light illuminated
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECM monitors the voltage and current supplied to the fuel injector circuit. It expects the injector to switch on and off at precise intervals with normal voltage levels. When voltage remains abnormally high or the circuit resistance is too low, the ECM detects a fault.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Injector Circuit Voltage 12-14V with proper switching pulses Sustained high voltage >14.5V or shorted circuit
Injector Resistance 10-15 ohms <5 ohms indicating short to ground
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Fuel injector connector
Inspect and reseat the connector at cylinder 9 injector to ensure clean contact and proper seating.
2
Wiring harness to injector 9
Check for damaged insulation, pinched wires, or exposed conductors causing a short to ground.
3
Fuel injector assembly
Replace the faulty injector if resistance tests confirm internal short or winding failure.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P0287 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P0287

What happens after you fix the fault

Once the fault is repaired, P0287 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.