Fuel Mode Indicator Lamp Control Circuit Malfunction
The P2668 code indicates a problem in the fuel mode indicator lamp control circuit. This circuit is responsible for illuminating the fuel mode indicator on the dashboard, which shows the current fuel system operating mode (e.g., open or closed loop). The Powertrain Control Module (PCM) monitors the circuit for electrical faults such as shorts, opens, or excessive resistance. When a fault is detected, the PCM sets this code and may disable the indicator lamp.
01. Most Common Causes
- Faulty fuel mode indicator lamp bulb or LED
- Open or shorted wiring in the indicator lamp circuit
- Damaged connector or poor electrical connection
- Failed PCM (rare)
02. Symptoms You Will Notice
- Fuel mode indicator lamp does not illuminate when expected
- Check Engine Light may be on
- No noticeable drivability issues in most cases
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for related codes.
Step 2: Visually inspect the fuel mode indicator lamp bulb/LED and replace if burned out.
Step 3: Check wiring and connectors for damage, corrosion, or loose connections; repair as needed.
Step 4: Test circuit continuity and voltage with a multimeter; compare to manufacturer specs.
Step 5: If all else fails, consider PCM replacement or reprogramming.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive because the code only affects the indicator lamp, not the fuel system operation. However, you may not be aware of the fuel mode status, which could be important for diagnostics.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, depending on the cause. Replacing a bulb or repairing wiring is inexpensive, while PCM replacement can be more costly.