Cylinder 9 Injector Circuit High
The P0286 code indicates that the Engine Control Module (ECM) has detected a high voltage or resistance in the electrical circuit for the fuel injector on cylinder 9. This typically means the injector circuit is open or shorted to voltage, often due to a faulty injector, damaged wiring, or a poor connection. The ECM monitors the injector driver circuit and sets this code when the voltage is above the expected range, which can prevent proper fuel delivery to cylinder 9.
1. Most Common Causes
- Faulty fuel injector on cylinder 9 or injector with high internal resistance
- Injector wiring shorted to battery positive voltage (B+)
- Corroded, loose, or damaged injector connector
- Open circuit in the injector control wire
- Internal ECM/PCM failure (less common)
- Excessive resistance in wiring harness connections
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire or rough idle
- Reduced engine power and poor acceleration
- Increased fuel consumption
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the injector connector and wiring for damage, corrosion, or loose pins.
Step 3: Measure resistance of cylinder 9 injector and compare to specification (typically 12-16 ohms).
Step 4: Check for voltage at the injector connector with key on (should see battery voltage on one pin).
Step 5: Perform a continuity test between the injector and ECM to check for open or short circuits.
Step 6: If wiring and injector are good, test the ECM injector driver (may require professional scan tool).
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause engine misfire, reduced performance, and potential damage to the catalytic converter. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including parts and labor. A new injector costs $50-$150, and labor is about $100-$250 depending on vehicle accessibility.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.