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P0203Cylinder 3 Injector "A" Circuit/Open

What it means

The ECU sees an electrical fault in the injector circuit of cylinder 3, usually an open circuit. The injector may not open at all, so that cylinder misfires.

Symptoms

  • Misfire on cylinder 3
  • Rough idle and loss of power
  • Check engine light, sometimes flashing

Common causes

  • Open injector winding (cylinder 3)
  • Broken wire or corroded injector connector
  • Open injector supply (fuse or relay)
  • ECU injector driver fault

What to check first

  1. Measure the injector resistance and compare it with the others
  2. Check the supply voltage at the injector connector with the key on
  3. Scope the injector control: look for the switching and the inductive spike
Can I drive with P0203? Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind P0203

Petrol fuel injector (port injection)Wiring, typical values, multimeter and scope testsCommon-rail diesel injectorWiring, typical values, multimeter and scope tests

Known engine problems that set P0203

1.9 TDI PD: Injector wiring loom under the cam coverVolkswagen, Audi, Skoda, Seat, Ford · typically 150,000–300,000 km

Cases with P0203 (0)

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P0203: questions and answers

What does P0203 mean?

P0203: Cylinder 3 Injector "A" Circuit/Open. The ECU sees an electrical fault in the injector circuit of cylinder 3, usually an open circuit. The injector may not open at all, so that cylinder misfires.

What are the symptoms of P0203?

Misfire on cylinder 3. Rough idle and loss of power. Check engine light, sometimes flashing.

What causes P0203?

Open injector winding (cylinder 3). Broken wire or corroded injector connector. Open injector supply (fuse or relay). ECU injector driver fault.

How do you diagnose P0203?

1. Measure the injector resistance and compare it with the others 2. Check the supply voltage at the injector connector with the key on 3. Scope the injector control: look for the switching and the inductive spike

Can I drive with P0203?

Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.