Injector Circuit Malfunction - Cylinder 4
The P0204 code indicates a malfunction in the electrical circuit of the fuel injector for cylinder 4. This means the powertrain control module (PCM) has detected an open or short circuit in the injector wiring, or a faulty injector itself. This disrupts fuel delivery to cylinder 4, causing misfires, rough idle, and potential engine damage if ignored.
1. Most Common Causes
- Faulty injector on cylinder 4 (open or shorted coil)
- Open or short-to-ground/short-to-voltage in the injector 4 control circuit wiring
- Loose, corroded, or damaged terminals at injector 4 connector
- Internal failure of the injector 4 driver (transistor) inside the PCM/ECM
- Issues in the injector voltage supply circuit (fuse, relay, wiring)
2. Symptoms You Will Notice
- Engine misfire on cylinder 4
- Rough idle and hesitation
- Check Engine Light illuminated
- Decreased fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0204 is present.
Step 2: Visually inspect injector connector and wiring for damage or corrosion.
Step 3: Use a multimeter to test injector resistance (should be 11-18 ohms).
Step 4: Swap injector with another cylinder to see if code follows.
Step 5: Check for 12V power and ground signal at injector harness with key on.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a misfire can damage the catalytic converter and cause further engine issues.
How much does it cost to fix?▼
Typically $50-$150 for a DIY injector replacement, or $150-$400 at a shop including labor.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.