What Does P0280 Mean?
The ECM has detected an excessively high voltage or current in the cylinder 7 fuel injector circuit. This code is found on V8 and larger engines and indicates the cylinder 7 injector driver circuit is seeing elevated electrical values due to a shorted injector, wiring fault, or ECM driver issue. The driver may notice rough running, black smoke, engine knock, or the ECM may shut down cylinder 7 fueling as a protective measure.
Common Causes
35%
Short to battery voltage in the cylinder 7 injector wiring harness
30%
Cylinder 7 fuel injector with internal short circuit (low coil resistance)
15%
Corroded or heat-damaged connector at the cylinder 7 injector
12%
ECM injector driver transistor failure for the cylinder 7 output
8%
Wiring harness routed near exhaust causing insulation melt and shorts
Diagnostic Steps
1
Measure cylinder 7 injector resistance at the connector — compare to factory spec. V8 diesel injectors typically read 0.5-1.5 ohms (piezo) or 0.3-0.9 ohms (solenoid). A significantly low value confirms an internal short.
2
Disconnect the injector and test the harness pins for short to voltage and short to ground — use a DVOM to check from each pin to B+ and from each pin to chassis ground.
3
Inspect the cylinder 7 injector connector and wiring path — on V8 engines, cylinder 7 wiring often routes near the exhaust manifold or turbo; look for heat-damaged insulation, melted connectors, or chafed wires.
4
Use a current clamp and oscilloscope to capture the cylinder 7 injector current waveform — look for abnormal peak current, excessive hold current, or waveform artifacts indicating a short.
5
Swap the cylinder 7 injector with cylinder 8 (or another nearby cylinder), clear codes, and run — if the code follows the injector, replace it.
Estimated Repair Cost
$100 - $900
Parts + labor, varies by vehicle and location
The ECM has detected an excessively high voltage or current in the cylinder 7 fuel injector circuit. This code is found on V8 and larger engines and indicates the cylinder 7 injector driver circuit is seeing elevated electrical values due to a shorted injector, wiring fault, or ECM driver issue. The...
The most common cause of P0280 (Cylinder 7 Injector Circuit High) is: Short to battery voltage in the cylinder 7 injector wiring harness
Typical repair costs for P0280 range from $100 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
An injector circuit stuck high can cause excessive fueling, engine knock, and catalytic converter overheating. Avoid towing or heavy loads and have it diagnosed and repaired promptly to prevent engine damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0280 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
