What Does P0277 Mean?
The ECM has detected an excessively high voltage or current in the cylinder 6 fuel injector circuit. This indicates the injector is drawing more current than normal, there is a short to voltage in the wiring, or the ECM driver is malfunctioning. Found on 6+ cylinder engines. The driver may notice rough running from cylinder 6 overfueling, black or white smoke, and possible engine knock.
Common Causes
35%
Short to battery voltage in the cylinder 6 injector wiring harness
30%
Cylinder 6 fuel injector with internal short circuit (low resistance)
15%
Damaged or corroded connector at the cylinder 6 injector
12%
ECM injector driver circuit failure for cylinder 6 output
8%
Adjacent cylinder wire shorted to cylinder 6 injector circuit
Diagnostic Steps
1
Measure cylinder 6 injector resistance with a DVOM — compare to factory specification. A reading significantly below the minimum indicates an internally shorted coil.
2
Disconnect the cylinder 6 injector and measure from each harness pin to battery positive and chassis ground — any continuity to voltage indicates a wiring short that needs to be traced.
3
Inspect the cylinder 6 injector connector for heat damage, melted plastic, fuel contamination, or corroded pins — these are common on rear-bank cylinders near exhaust components.
4
Monitor the cylinder 6 injector current waveform using a current clamp and compare peak current draw to other cylinders — the waveform shape and magnitude should be nearly identical.
5
Swap the cylinder 6 injector with another cylinder, clear codes, and test-drive — if the high circuit code follows the injector, it is internally shorted and needs replacement.
Estimated Repair Cost
$100 - $800
Parts + labor, varies by vehicle and location
The ECM has detected an excessively high voltage or current in the cylinder 6 fuel injector circuit. This indicates the injector is drawing more current than normal, there is a short to voltage in the wiring, or the ECM driver is malfunctioning. Found on 6+ cylinder engines. The driver may notice ro...
The most common cause of P0277 (Cylinder 6 Injector Circuit High) is: Short to battery voltage in the cylinder 6 injector wiring harness
Typical repair costs for P0277 range from $100 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Overfueling on cylinder 6 from a high injector circuit can cause engine knock, catalytic converter overheating, or exhaust system damage. Avoid heavy loads and sustained high-RPM operation until diagnosed.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0277 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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