P0203 Injector Circuit Malfunction - Cylinder 3

P0203 points to an injector circuit malfunction on cylinder 3. The code identifies the injector control circuit that needs electrical testing.

Code details

Generic OBD-II · P0

System: Injector
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not treat P0203 as a fuel-quality or spark-plug issue first; the named path is the cylinder 3 injector circuit.

Symptoms of P0203

Check-engine light, often with a misfire feel from one cylinder.
Rough idle, hesitation, or a slight loss of power.
Higher fuel use, or in some cases a fuel smell.

Common causes of P0203

A stuck, leaking, clogged, or electrically failed injector.
Injector wiring, connector, or driver-circuit faults.
Low fuel pressure or contamination affecting injector behaviour.

Useful checks before replacing parts

Inspect cylinder 3 injector connector condition, terminal tension, wiring continuity, power feed, and control signal.
Compare injector current, resistance, or balance results against known-good cylinders when the vehicle supports it.
Use misfire data and fuel trims to separate injector-circuit failure from fuel delivery or compression problems.

Related OBD-II codes

These nearby injector entries can help compare wording and pin down the fault area.