Fuel and air

P0280 — Cylinder 7 Injector Circuit High

Severity: medium Drive with care, to a shop

What P0280 means

The engine control module fires the cylinder 7 injector by supplying power and switching the ground side through an internal driver. P0280 sets when voltage or current in that circuit is higher than expected. The cause may be the injector itself, damaged wiring, or a failed driver inside the module.

Symptoms

  • Check engine light on
  • Rough running or misfire on cylinder 7
  • Loss of power or hesitation
  • Worse fuel economy
  • Unstable idle
  • Hard starting (sometimes)

Possible causes

  1. Faulty cylinder 7 injector (internal winding fault or short)
  2. Damaged wiring harness or poor connection at the injector connector
  3. Injector wire shorted to battery voltage
  4. Corroded or loose terminals at the ECM connector
  5. Failed injector driver inside the ECM
  6. Problem in the injector power supply (relay or fuse)

How to diagnose

  1. Scan all codes and freeze frame data, and note any other injector or misfire codes
  2. Inspect the cylinder 7 injector connector and harness for chafing, oil contamination, corrosion or melting
  3. Measure injector resistance and compare it with specifications and with neighboring injectors
  4. Check supply voltage at the connector and test the signal wire for a short to power
  5. Swap the injector with a known good one to see whether the code follows it
  6. Check the ECM control pulse with a scope or injector tester
  7. Check fuel pressure and fuel trims, and rule out intake or exhaust leaks
  8. If wiring and injector are fine, verify ECM power and grounds before suspecting the driver

Common fixes

  • Replace the faulty cylinder 7 injector
  • Repair or replace the damaged wiring harness or connector
  • Clean and restore loose or corroded terminals
  • Repair or replace the ECM if the driver has failed
  • Clear codes after repair and verify fuel trims

Questions and answers

What does P0280 mean?

It means the ECM saw abnormally high voltage or current in the cylinder 7 injector circuit. The usual causes are a bad injector or wiring, and less often the control module.

Can I drive with P0280?

Only briefly and carefully, such as to a shop. Misfires and excess fuel can damage the catalytic converter, and if the engine runs very rough you should not drive.

How can I tell if it is the injector or the wiring?

Measure the injector resistance and inspect the harness. You can also swap the injector with a good one: if the code moves with it, the injector is bad.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.