Cylinder 1 Injector Circuit Low
P0261 indicates that the fuel injector for cylinder 1 is receiving insufficient electrical voltage or current from the PCM. This causes the injector to spray less fuel into that cylinder, creating a lean mixture that triggers the check engine light and can damage the engine over time.
What You Might Notice
- Check engine light illuminated
- Rough idle or rough running engine
- Loss of engine power
- Significant drop in fuel economy
- Possible misfiring in cylinder 1
Most Common Causes
- 1
Dirty or clogged fuel injector
Fuel deposits block the injector spray pattern, reducing fuel delivery to cylinder 1. Cleaning or replacing the injector resolves the issue.
- 2
Faulty fuel injector
The injector coil has failed or lost resistance, preventing proper solenoid activation. The injector must be replaced.
- 3
Damaged wiring or connector
Corroded, cut, or loose wiring to the cylinder 1 injector reduces voltage delivery. Inspect connectors and repair or replace damaged wiring.
- 4
PCM or driver circuit failure
The powertrain control module's injector driver circuit is faulty, unable to supply proper voltage to the injector. PCM repair or replacement may be necessary.
How to Diagnose It
- 1
Check Dirty or clogged fuel injector — Fuel deposits block the injector spray pattern, reducing fuel delivery to cylinder 1. Cleaning or replacing the injector resolves the issue.
- 2
Check Faulty fuel injector — The injector coil has failed or lost resistance, preventing proper solenoid activation. The injector must be replaced.
- 3
Check Damaged wiring or connector — Corroded, cut, or loose wiring to the cylinder 1 injector reduces voltage delivery. Inspect connectors and repair or replace damaged wiring.
- 4
Check PCM or driver circuit failure — The powertrain control module's injector driver circuit is faulty, unable to supply proper voltage to the injector. PCM repair or replacement may be necessary.
How to Fix It
- 1
Clean or replace fuel injector
Remove the fuel injector for cylinder 1 and either clean it with fuel injector cleaner and ultrasonic cleaning or replace it with a new unit. Reinstall and verify the code clears.
- 2
Inspect and repair wiring and connectors
Check the fuel injector connector and wiring harness for corrosion, loose connections, or damage. Clean connectors with electrical contact cleaner and repair or replace damaged wiring.
- 3
Test fuel injector resistance
Use a multimeter to measure the injector resistance. Proper range is typically 10-16 ohms. If out of range, the injector is faulty and must be replaced.
- 4
Test PCM injector circuit and replace if necessary
Have the PCM inspected by a professional or use advanced diagnostics to test the injector driver circuit. If the PCM is faulty, it will require reprogramming or replacement.
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