What Does P0286 Mean?
The ECM has detected an excessively high voltage or current in the cylinder 9 fuel injector circuit. This code is found on engines with 9 or more cylinders (V10, V12, or inline-6 diesel with dual-bank injection). The cylinder 9 injector driver circuit is reporting electrical values above the expected range, indicating a shorted injector, wiring fault, or ECM driver issue. The driver may notice rough running, excessive smoke, or engine knock.
Common Causes
35%
Short to battery voltage in the cylinder 9 injector wiring
30%
Cylinder 9 fuel injector with internal short circuit (low resistance)
15%
Damaged or corroded connector at the cylinder 9 injector
12%
ECM injector driver failure for the cylinder 9 output
8%
Wiring routed near high-heat source causing insulation breakdown
Diagnostic Steps
1
Measure cylinder 9 injector coil resistance with a DVOM — compare to factory specification for the specific engine. A reading significantly below minimum spec confirms an internal short.
2
Disconnect the cylinder 9 injector and check the harness for shorts to voltage and shorts to ground — measure from each pin to B+ and each pin to chassis ground.
3
Inspect the cylinder 9 injector connector for heat damage, fuel contamination, moisture intrusion, or corroded terminals — V10/V12 engines often have long harness runs exposed to harsh conditions.
4
Use a current clamp and oscilloscope to capture the cylinder 9 injector waveform — compare peak and hold current values to known-good cylinders on the same bank.
5
Swap cylinder 9 injector with an adjacent cylinder, clear codes, and run the engine — if the high circuit code follows the injector, it has an internal fault.
Estimated Repair Cost
$150 - $1,000
Parts + labor, varies by vehicle and location
The ECM has detected an excessively high voltage or current in the cylinder 9 fuel injector circuit. This code is found on engines with 9 or more cylinders (V10, V12, or inline-6 diesel with dual-bank injection). The cylinder 9 injector driver circuit is reporting electrical values above the expecte...
The most common cause of P0286 (Cylinder 9 Injector Circuit High) is: Short to battery voltage in the cylinder 9 injector wiring
Typical repair costs for P0286 range from $150 to $1,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Overfueling from a shorted injector circuit can cause engine knock, exhaust component damage, and catalytic converter overheating. Limit driving to short distances at low load until diagnosed and repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0286 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Generic (SAE)
Recommended Tools
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