Injector Circuit Malfunction - Cylinder 4
The PCM detected a circuit malfunction in the fuel injector for cylinder 4, either in the injector itself or its wiring harness. This causes incomplete or no fuel delivery to that cylinder, resulting in misfires and rough engine operation.
What You Might Notice
- Engine misfire on cylinder 4
- Rough or uneven idle
- Poor acceleration and reduced power
- Check Engine Light (MIL) illuminated
- Possible fuel smell from exhaust
Most Common Causes
- 1
Faulty fuel injector
The injector for cylinder 4 is stuck open, stuck closed, or internally damaged, preventing proper fuel atomization or delivery.
- 2
Open or broken wiring to injector
A break in the electrical circuit connecting the PCM to the injector, preventing the signal from reaching the injector coil.
- 3
Short in injector wiring or connector
A short circuit in the harness or connector grounds the injector circuit prematurely, blocking proper operation.
- 4
Defective PCM or injector driver
The PCM's fuel injector driver circuit or the PCM itself has failed, unable to command the cylinder 4 injector.
How to Diagnose It
- 1
Check Faulty fuel injector — The injector for cylinder 4 is stuck open, stuck closed, or internally damaged, preventing proper fuel atomization or delivery.
- 2
Check Open or broken wiring to injector — A break in the electrical circuit connecting the PCM to the injector, preventing the signal from reaching the injector coil.
- 3
Check Short in injector wiring or connector — A short circuit in the harness or connector grounds the injector circuit prematurely, blocking proper operation.
- 4
Check Defective PCM or injector driver — The PCM's fuel injector driver circuit or the PCM itself has failed, unable to command the cylinder 4 injector.
How to Fix It
- 1
Replace fuel injector for cylinder 4
Remove and replace the faulty injector with an OEM or quality aftermarket unit. This is the most common repair for this code.
- 2
Inspect and repair injector wiring harness
Check the wiring and connectors leading to cylinder 4 injector for breaks, corrosion, or loose connections. Repair or replace damaged wiring as needed.
- 3
Test PCM and injector driver circuit
Use a diagnostic scanner and multimeter to verify the PCM is sending proper signals to the injector. If signals are absent or faulty, the PCM may need replacement or reprogramming.
- 4
Clear code and road test
After repairs, clear the DTC using a diagnostic scanner and perform a test drive to confirm the misfire is resolved and the code does not return.
Need a deeper diagnosis?
Search for related repair guides or browse by system.