Cylinder 5 Injector Circuit Low
P0273 indicates the fuel injector circuit for cylinder 5 is operating at a lower voltage or current than expected. This causes incomplete fuel atomization, resulting in a lean mixture in that cylinder that triggers the oxygen sensor to signal the PCM to richen the fuel delivery to all cylinders, degrading fuel economy and engine performance.
What You Might Notice
- Check engine light illuminated with P0273 code
- Engine running rough or misfiring
- Lack of engine power and acceleration
- Significant decrease in fuel economy
- Possible cylinder 5 knocking or pinging under load
Most Common Causes
- 1
Dirty or clogged fuel injector
Cylinder 5 fuel injector may be partially blocked by fuel deposits or contamination, restricting spray pattern and causing lean operation in that cylinder.
- 2
Faulty fuel injector
The injector solenoid or internal components may be failing, resulting in reduced opening time or incomplete atomization despite proper electrical signal.
- 3
Injector wiring or connector issues
Corroded, loose, or damaged wiring and connectors in the cylinder 5 injector circuit can cause voltage drop and reduced current flow to the injector.
- 4
PCM or fuel injector driver malfunction
The powertrain control module's injector driver circuit may be weakened or failing, reducing the signal strength sent to the cylinder 5 injector.
How to Diagnose It
- 1
Check Dirty or clogged fuel injector — Cylinder 5 fuel injector may be partially blocked by fuel deposits or contamination, restricting spray pattern and causing lean operation in that cylinder.
- 2
Check Faulty fuel injector — The injector solenoid or internal components may be failing, resulting in reduced opening time or incomplete atomization despite proper electrical signal.
- 3
Check Injector wiring or connector issues — Corroded, loose, or damaged wiring and connectors in the cylinder 5 injector circuit can cause voltage drop and reduced current flow to the injector.
- 4
Check PCM or fuel injector driver malfunction — The powertrain control module's injector driver circuit may be weakened or failing, reducing the signal strength sent to the cylinder 5 injector.
How to Fix It
- 1
Clean fuel injector
Remove and professionally clean cylinder 5 fuel injector using ultrasonic or chemical cleaning service, or replace with a new injector if cleaning is ineffective.
- 2
Inspect and repair injector wiring
Check the cylinder 5 injector harness connector and wiring for corrosion, damage, or loose connections. Clean contacts or replace damaged wiring as needed.
- 3
Test fuel pressure and injector resistance
Verify fuel pressure at the rail meets specifications and test the injector coil resistance with a multimeter to confirm the injector is functioning properly.
- 4
Replace fuel injector
If cleaning and electrical checks fail, replace the cylinder 5 fuel injector with an OEM or equivalent quality unit and clear the code to verify resolution.
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