P0203
Fuel Injector Circuit/Open - Cylinder 3
The engine computer is not happy with the electrical circuit for injector 3. That can stop cylinder 3 from getting fuel correctly and lead to a rough idle, misfires, and poor acceleration.
- SEV
- 4/5
- DRIVE
- CAUTION
- DIY
- $20-$250
- SHOP
- $150-$700
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Faulty cylinder 3 fuel injector
- Loose, corroded, or damaged injector 3 connector or harness
- Open or short in the injector 3 power or control circuit
Typical repair cost
DIY usually runs $20-$250. Typical shop repair lands around $150-$700, depending on the root cause.
01 / Definition
P0203 means the PCM found an electrical problem in the fuel injector circuit for cylinder 3. The injector may be open, shorted, have abnormal resistance, or fail to respond properly when the PCM commands injector pulse width.
02 / Drive status
With caution. The vehicle may still move, but a cylinder 3 injector circuit fault can quickly turn into a strong misfire. Avoid extended driving so the catalytic converter is not overheated by unburned fuel.
03 / Symptoms
- Check engine light
- Misfire under load
- Rough idle
- Poor acceleration
- Increased fuel consumption
04 / Causes
| 1 | Faulty cylinder 3 fuel injector | high |
|---|---|---|
| 2 | Loose, corroded, or damaged injector 3 connector or harness | high |
| 3 | Open or short in the injector 3 power or control circuit | medium |
| 4 | PCM injector driver problem | medium |
05 / Diagnostic sequence
- 01Confirm P0203 and note any cylinder 3 misfire or fuel trim data.
- 02Inspect the cylinder 3 injector connector for corrosion, looseness, or oil contamination.
- 03Check the injector harness routing for melted insulation or pinched wiring.
- 04Measure injector resistance and compare it with neighboring injectors.
- 05Verify injector pulse and power feed with a noid light, meter, or scope before replacing the PCM.
06 / Repairs
| 1 | Repair cylinder 3 injector wiring, connector damage, or poor terminal fit | $20-$150 |
|---|---|---|
| 2 | Replace the faulty cylinder 3 fuel injector | $50-$300 |
| 3 | Repair driver circuit or PCM faults if injector command is missing | $150-$700 |
07 / Related codes
08 / FAQ
Can P0203 feel like a bad spark plug?
Yes. A dead injector can make the engine shake and misfire in a way that feels similar to an ignition problem.
Should I replace injector 3 first?
Not before checking the connector, wiring, and injector resistance. Electrical faults outside the injector are common.
Can P0203 appear with misfire codes?
Yes. P0203 often shows up with cylinder 3 misfire or fuel trim codes because the cylinder is not being fueled correctly.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.