P0203: Injector Circuit/Open, Cylinder 3
The engine computer sees an open or faulty electrical circuit for the cylinder 3 fuel injector. That cylinder may not be getting fuel.
Green, yellow, red: three ways P0203 can look
The same code can be a quick fix or a reason to pull over. Match your situation to the closest example.
Keep an eye on it
Code set once, engine smooth.
Schedule a repair
Rough running on cylinder 3. Repair soon.
Stop and get help
Heavy misfire or flashing light. Stop driving soon.
Symptoms you might notice
- Misfire on that cylinder
- Rough idle
- Power loss
Common causes, cheapest first
- Unplugged or corroded injector connector on cylinder 3
- Failed injector coil on cylinder 3
- Damaged injector wiring
- Engine computer driver fault (rare)
What you can check before calling
- Check that the cylinder 3 injector connector is attached
A code points to a system, not a part. Replacing parts based on the code alone is how people spend money without fixing the problem. Testing confirms the cause first.
Generic codes (second character 0) mean the same thing on every vehicle. Some manufacturers add their own details, so check service information for your exact vehicle.
More fuel & air mixture codes
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does P0203 mean?
P0203 means "Injector Circuit/Open, Cylinder 3". The engine computer sees an open or faulty electrical circuit for the cylinder 3 fuel injector. That cylinder may not be getting fuel.
Can I drive with code P0203?
It depends on what the vehicle is doing. Green: Code set once, engine smooth. Yellow: Rough running on cylinder 3. Repair soon. Red: Heavy misfire or flashing light. Stop driving soon.
What causes P0203?
The most common causes are: unplugged or corroded injector connector on cylinder 3; failed injector coil on cylinder 3; damaged injector wiring.
Is P0203 a serious code?
It can be. Heavy misfire or flashing light. Stop driving soon.
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