P0204 — Cylinder 4 Injector A Circuit

P0204: Cylinder 4 Injector A Circuit — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

Cylinder 4 Injector A Circuit. Basic catalogue definition; diagnostic details have not yet been reviewed.

Affected system: Powertrain

Symptoms

  • Check-engine lamp, rough idle or engine misfire; reduced power may occur.
  • An electrical problem is detected in the injector circuit for cylinder 4; this does not by itself prove a clogged nozzle.

Possible causes

  • Loose, corroded or broken connector and wiring at injector 4.
  • Injector coil/actuator fault; an engine-control driver fault is possible but must be proved separately.

What to check

  • Read P0204 with related misfire and supply-voltage faults before clearing memory.
  • Identify cylinder 4 using the manufacturer's numbering scheme, then inspect its injector connector and loom.
  • Perform an OEM-specified power, circuit continuity and driver-control test with ignition and high-pressure fuel safety precautions.
  • Compare injector electrical test results with the manufacturer’s data, without applying a universal resistance limit.
  • Repair wiring or replace the injector only when confirmed, then recheck code and cylinder contribution.

Also written as: P0204-00, P020400, PO204 (some scan tools add the fault-type byte, e.g. -00).