Peugeot P1121: Peugeot OBD-II Error Code P1121

Symptoms

The ECM has detected a fuel injector circuit fault. The engine may misfire or run on fewer cylinders. DTC P1121 is stored in the Peugeot engine control module.

Possible Causes

Fuel injector coil open or short
Injector driver circuit fault in ECM
Wiring to injector corroded
Injector mechanically stuck

Troubleshooting Steps

Step 1: Connect an OBD-II scanner and read DTCs to confirm P1121
DTC P1121 present with freeze frame data
Step 2: Inspect wiring and connectors in the affected circuit for damage, corrosion, or loose pins
Wiring intact, connectors clean and seated
Step 3: Perform component-level testing per manufacturer service manual
Component values within spec or component confirmed faulty
Step 4: Repair or replace the faulty component, clear DTC, and verify no return
DTC cleared and does not return after a road test

How to Reset

Clear the DTC after repair using a diagnostic scanner. The code clears automatically if the fault is not detected for 3 consecutive drive cycles.

Common Replacement Parts

varies: Diagnose and replace the confirmed faulty component (Confirm part number via VIN at a Peugeot dealership)

Frequently Asked Questions

Q: What does P1121 mean?
This manufacturer-specific DTC indicates a fuel & air metering - injector system fault. Refer to the vehicle's service manual for the exact diagnostic procedure.
Q: Can I drive with P1121?
Limited driving is possible, but the affected system may not operate correctly. Have the vehicle diagnosed promptly to prevent potential damage.

Peugeot OBD-II Error Code P1121