P0204
Cylinder 4 Injector A Circuit
Fuel injector circuit
Generic OBD-II
High
What it means
P0204 means the ECM detected an electrical fault in the fuel-injector control circuit for cylinder 4 — an open, short, or wiring problem in that injector's circuit. If the injector stops delivering fuel, cylinder 4 goes dead and the engine misfires, runs rough, and loses power. Because a persistent misfire can overheat the catalytic converter, this is worth diagnosing before driving far.
High
Can I keep driving? Limit driving — an injector-circuit fault can leave cylinder 4 dead, causing a misfire that dumps raw fuel into the exhaust and can damage the catalytic converter.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle and a misfire on cylinder 4
- Reduced power and hesitation on acceleration
- Raw-fuel smell or increased fuel consumption
Common causes
Most likely first
- Failed fuel injector on cylinder 4 (open or shorted coil) — most commonLikely
- Open or damaged wiring in the cylinder-4 injector circuitCommon
- Loose or corroded injector connectorCommon
- Failed injector driver in the ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame and check for a matching cylinder-4 misfire code (P0304).
- Measure the cylinder-4 injector's coil resistance and compare to the other injectors.
- Inspect the injector connector and wiring for opens, shorts, or corrosion; check for the ECM's control pulse.
- Replace the injector if it's electrically open or shorted, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0204?+
Only briefly. If the circuit fault stops cylinder 4 from firing, the resulting misfire sends unburned fuel into the catalytic converter and can ruin it. Get it diagnosed before driving much.
Can I just clear P0204?+
It will return quickly if the injector or its wiring is still faulty. Repairing the circuit or replacing the injector is what actually clears it.
Related codes
Often seen with P0204
Read & clear P0204 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX