Injector Circuit Malfunction - Cylinder 3
The P0203 code indicates a problem in the electrical circuit of the fuel injector for cylinder 3. The Powertrain Control Module (PCM) has detected an abnormal voltage or resistance in the injector circuit, which can prevent the injector from opening properly. This leads to a misfire, reduced engine performance, and increased emissions. Common causes include a faulty injector, wiring issues, or a damaged PCM.
1. Most Common Causes
- Faulty fuel injector on cylinder 3
- Open or shorted wiring in injector circuit
- Corroded or loose connector at injector
- Damaged PCM (rare)
2. Symptoms You Will Notice
- Engine misfire or rough idle
- Check Engine Light illuminated
- Poor acceleration and reduced fuel economy
- Engine may run rich or lean
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect injector connector and wiring for damage or corrosion.
Step 3: Use a multimeter to check injector resistance (typically 12-16 ohms).
Step 4: Perform a power and ground test at the injector connector with key on.
Step 5: Swap injector with another cylinder to see if code follows.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended as it can cause engine misfire, damage the catalytic converter, and reduce fuel economy. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and injector replacement, but costs vary by vehicle and labor rates.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.