Code P0204: Explanations, Causes, and Solutions
Meaning of Code P0204
Code P0204 is a generic OBD-II code indicating a malfunction in the fuel injector circuit for cylinder #4. The Powertrain Control Module (PCM) detects an anomaly in the electrical signal or resistance of the injector circuit, outside the manufacturer’s specifications.
Role of the Injector:
- Inject fuel into the cylinder as commanded by the PCM.
- Optimize the air-fuel mixture for efficient combustion.
Severity of Code P0204
Severity Level: Moderate to High
Potential Risks:
- Engine running poorly (misfires, vibrations).
- Loss of power and hesitant acceleration.
- Catalytic converter damage if the mixture is too rich.
Recommended Action: Diagnose promptly to avoid costly damage.
Common Symptoms
- Illuminated check engine light.
- Misfires (especially at idle or under load).
- Weak acceleration or stumbling.
- Increased fuel consumption.
- Black smoke from the exhaust (rich mixture).
Possible Causes
- Faulty Injector:
- Burnt internal coil, resistance out of range.
- Clogged nozzle or fuel leak.
- Electrical Circuit Problem:
- Cut wires, short circuits, or damaged connector.
- PCM Failure (rare): Command or signal processing error.
Diagnosis and Repair
Required Tools:
- Digital multimeter (DVOM).
- OBD2 scan tool.
- Injector tester (optional).
Step 1: Check Injector Resistance
- Disconnect the injector connector for cylinder 4.
- Measure the resistance between the injector terminals:
- Normal value: 10 to 18 Ω (depending on model).
- If out of range ⇒ Replace the injector.
Step 2: Inspect the Electrical Circuit
- Check the supply voltage at the connector (≥ 10 V).
- Test continuity between the injector and the PCM.
- Look for damaged wires or corroded connectors.
Step 3: Test the Injector
- Use an injector tester to check its operation (characteristic click).
- If the injector does not work, replace it or test it on another cylinder.
Step 4: Check the PCM
- Disconnect the PCM connector and test the command wire (controlled ground).
- Warning: Handle the PCM with care.
Step 5: Code Reset
- Clear the P0204 code with the OBD2 tool.
- Perform a road test to confirm the repair.
Practical Tips
- Group Replacement: Inspect other injectors for similar wear.
- Injector Cleaning: Use a fuel additive or ultrasonic cleaning.
- Disconnect the battery before any electrical work.
Special Cases
- High-Impedance Injectors: Check manufacturer specifications.
- Piezo-Electric Injectors: Require advanced diagnostic tools.
Conclusion
Code P0204 typically indicates a faulty injector or wiring issue on cylinder 4. Prompt action prevents major complications. If electrical tests are complex, consult a mechanic for an accurate diagnosis.
🔧 Recommended Parts: OEM injector, wiring harness repair kit.