Cylinder 12 Injector Circuit Range/Performance
The P02F9 code indicates that the Engine Control Module (ECM) has detected a malfunction in the electrical circuit of the fuel injector for cylinder 12. This could be due to an open or short circuit, or the injector's performance is outside the expected range. The ECM monitors the injector's electrical characteristics, such as resistance and current draw, and triggers this code when they deviate from specifications. This issue can lead to incomplete combustion, misfires, and reduced engine performance.
01. Most Common Causes
- Faulty fuel injector on cylinder 12
- Open or short in the injector wiring harness
- Poor electrical connection at the injector or ECM
- Failed ECM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire or rough idle
- Reduced fuel economy
- Loss of power or hesitation during acceleration
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for additional codes.
Step 2: Visually inspect the injector connector and wiring for damage or corrosion.
Step 3: Measure the resistance of the injector on cylinder 12 and compare to specifications (typically 12-16 ohms).
Step 4: Perform a injector electrical test using a multimeter or oscilloscope to check for proper voltage and current.
Step 5: If wiring and injector are okay, test the ECM output for that injector circuit.
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 engine misfire, reduced performance, and potential damage to the catalytic converter. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including parts and labor. A single injector replacement costs $100-$250, plus diagnostic fees.