Fuel and air

P0294 — Cylinder 12 Injector Circuit Low

Severity: medium Drive with care, to a shop

What P0294 means

The engine control module (ECM) fires each fuel injector by switching its circuit to ground with a driver, and it monitors the voltage in that circuit. P0294 sets when the circuit reads lower than expected, which points to an open, a short, a poor connection, a bad injector or a failed driver in the ECM. The code applies to engines with 12 cylinders, such as V12s.

Symptoms

  • Check Engine light on
  • Rough idle
  • Misfires or hesitation
  • Loss of power
  • Higher fuel consumption
  • Raw fuel smell from the exhaust

Possible causes

  1. Open or shorted wiring in the cylinder 12 injector circuit
  2. Corroded or loose injector connector
  3. Faulty fuel injector (bad coil or internal short)
  4. Injector wire shorted to ground
  5. Failed injector driver inside the ECM
  6. Low system voltage from a weak battery or charging problem

How to diagnose

  1. Scan for codes and freeze-frame data, and note any other injector or misfire codes
  2. Test battery voltage and charging system output
  3. Inspect the cylinder 12 injector connector and harness for corrosion, chafing and damaged insulation
  4. Measure injector coil resistance and compare it with the specification
  5. Check the power and control wires for opens and shorts to ground
  6. Swap the injector with a neighboring cylinder and see whether the fault follows it
  7. Check the control signal with a scope or noid light while cranking or running
  8. If wiring and injector are good, test the ECM driver

Common fixes

  • Repair damaged wiring and connector terminals
  • Replace the cylinder 12 fuel injector
  • Charge or replace the battery and fix any charging fault
  • Repair, replace or reprogram the ECM

Questions and answers

What does P0294 mean?

The ECM detected a low signal in the cylinder 12 injector circuit. The usual culprits are the wiring, the connector or the injector itself.

Can I drive with P0294?

Only briefly and carefully, to get to a shop. Misfires can damage the catalytic converter, so don't put the repair off.

How do I fix P0294?

Start with the injector connector and wiring, then test the injector's resistance. If those are fine, the ECM may be at fault. After the repair, clear the code and confirm it doesn't return.

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.