What does P0203 mean?
The control module detected a condition described as “Fuel injector cylinder 3 – circuit”. The code identifies the affected area, but it does not by itself prove which component has failed. The code describes the detected condition, not a guaranteed failed part. A reliable diagnosis also considers related codes, freeze-frame data, live values and the actual symptoms.
Possible causes
- Electrical fault at the fuel injector
- Faulty or contaminated injector
- Poor connection in the engine wiring harness
- Control-module driver or supply-voltage fault
Common symptoms
- Very rough engine operation
- Misfiring and power loss
- Difficult starting
- Fuel smell or increased consumption
Sensible next checks
- Compare cylinder-specific faults and misfire counters
- Inspect the connector and wire to the affected injector
- Measure resistance or current draw to manufacturer specifications
- Open direct-injection fuel systems only with appropriate professional procedures
Why does it return after clearing?
Clearing the code only removes the stored entry. If the underlying condition remains, the control module will set the code again after the next relevant monitor cycle. Save the data first, diagnose the cause, repair it and only then clear the code.