P0204
UniversalInjector Circuit Malfunction - Cylinder 4
Medium SeverityThis code indicates an electrical problem with the fuel injector circuit for cylinder 4. This malfunction typically prevents the fuel injector from delivering the correct amount of fuel, leading to engine misfires and reduced performance.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before working on electrical components. Allow the engine to cool down before handling hot parts. Be cautious when working with fuel lines, as fuel is flammable and under pressure.
Common Symptoms
- Check Engine Light illuminated
- Engine misfire
- Rough idle
- Reduced engine power
- Poor fuel economy
- Engine hesitation or stumbling
- Engine may run lean or rich on cylinder 4
Common Causes
- Faulty fuel injector for cylinder 4
- Open or short in the fuel injector wiring harness for cylinder 4
- Poor electrical connection at the injector or ECU
- Faulty Engine Control Unit (ECU) (less common)
- Damaged driver circuit within the ECU
Frequently reported on: Honda Civic (2006-2011), Ford F-150 (2004-2008), Toyota Camry (2002-2006), Chevrolet Silverado (2007-2013), Nissan Altima (2002-2006)
Diagnostic Steps
- Visually inspect the wiring harness and connectors for cylinder 4's fuel injector for any obvious damage, corrosion, or loose connections.
- Using a multimeter, check for proper voltage supply to the fuel injector.
- Test the resistance of the fuel injector itself; compare to manufacturer specifications.
- If accessible, swap the cylinder 4 injector with another cylinder's injector (if symptoms follow the injector, it's faulty).
- Check for continuity and shorts in the injector's signal wire between the injector connector and the ECU connector.
👨🔧 When to Call a Professional
If you are unable to definitively pinpoint the cause after basic diagnostic steps, or if the issue involves complex wiring beyond a simple visible repair, it is best to consult a qualified mechanic to avoid further damage.
Commonly Asked Questions
Can I drive with a P0204 code?
While it is possible, it is not recommended. Driving with a misfire can lead to reduced power, poor fuel economy, and potential damage to your catalytic converter over time.
How do I test if the fuel injector itself is bad?
You can test the injector's electrical resistance with a multimeter. Compare the reading to your vehicle's service manual specifications. You can also listen for a clicking sound with a stethoscope when the engine is running or use a noid light to check the pulse.
Is it possible for a bad spark plug or coil pack to cause a P0204 code?
No, a P0204 specifically indicates an electrical malfunction in the injector circuit. While a bad spark plug or coil pack would cause a misfire (potentially a P0304 code), they do not directly cause a P0204.
What is the typical cost to replace a fuel injector?
The cost can vary significantly depending on the vehicle, but typically a single fuel injector part can range from $50-$200. Labor costs would be additional, often 1-3 hours depending on accessibility.
Do I need to replace all fuel injectors if one is bad?
Not necessarily. If diagnostics confirm only cylinder 4's injector circuit is faulty, replacing just that injector or repairing its wiring should resolve the P0204 code. However, if other injectors are old or show signs of wear, it might be a good time to consider replacing them.