P0204 Injector Circuit Malfunction - Cylinder 4

P0204 points to an injector circuit malfunction on cylinder 4. The control module detected a problem in the electrical path for that injector.

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 replace cylinder 4 parts blindly; a damaged harness, loose terminal, or control-driver issue can set the same code.

Symptoms of P0204

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 P0204

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

Check cylinder 4 injector power, control circuit, connector fit, terminal tension, and harness routing near heat or vibration.
Compare injector resistance, current ramp, or balance data with other cylinders if testing equipment is available.
Review misfire counters and fuel-trim behavior to determine whether the circuit fault matches the symptom.

Related OBD-II codes

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