Injector Circuit Malfunction - Cylinder 3
The P0203 code indicates a problem in the electrical circuit of the fuel injector for cylinder 3. This could be due to an open or short circuit in the wiring, a faulty injector, or a problem with the engine control module (ECM). The ECM monitors the injector circuit for proper voltage and current; when it detects an anomaly, it sets this code. This can cause cylinder 3 to misfire, leading to rough idling, poor acceleration, and increased emissions.
01. Most Common Causes
- Faulty fuel injector on cylinder 3
- Open or short circuit in injector wiring or connector
- Damaged ECM or poor ECM connection
- Corroded or loose electrical connections
02. Symptoms You Will Notice
- Engine misfire on cylinder 3
- Rough idle or hesitation during acceleration
- Check Engine Light illuminated
- Decreased fuel economy and performance
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0203 and check for other codes.
Step 2: Visually inspect the injector connector and wiring for damage, corrosion, or loose connections.
Step 3: Measure resistance of injector 3; compare to specification (typically 12-16 ohms).
Step 4: Check for power and ground at injector connector with key on; if missing, trace circuit back to ECM.
Step 5: Swap injector 3 with another cylinder; if code moves, replace injector. If not, check ECM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can cause catalytic converter damage and poor engine performance. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Injector replacement ranges from $150-$400 per injector including labor, depending on vehicle.