What P0203 means
Injector Circuit Malfunction – Cylinder 3
How to diagnose
- Read freeze frame data. When P0203 set, your ECU snapshotted every sensor at that moment. This tells you what the car was doing when the fault triggered — RPM, load, coolant temp, throttle position, fuel trims. Almost always enough info to figure out the cause without further testing.
- Check for related codes. If you have P0203 plus other codes, fix the earliest one in the chain first — a single root cause often triggers multiple codes.
- Cheap fixes first. For most codes, the order is: inspect connectors + wiring (free), check for vacuum leaks (cheap), replace sensor (moderate), replace mechanical part (expensive). Follow that ladder before dropping money on parts.
Manufacturer-specific descriptions
Different manufacturers use P0203 for slightly different failure modes:
| AUDI | Fuel injector failure, Powertrain Control Module (PCM) failure, Wiring issue |
| BMW | Injector Circuit/Open - Cylinder 3 |
| FIAT | Injector 3 (open circuit) |
| FORD | Injector Circuit Malfunction - Cylinder #3 |
| MITSUBISHI | Injector Circuit Malfunction - Cylinder 3; No.3 injector system |
| NISSAN | Injector Circuit Malfunction - Cylinder 3 |
| VOLKSWAGEN | Injector 3 Control Circuit |
Read P0203 on your own car
DIY Fix My Car reads P0203 plus 25,000+ other DTC codes with manufacturer-specific descriptions. Includes freeze frame data, likely fix parts, and AI mechanic chat. Download free.