MIL Control Circuit Malfunction (P0650)
The P0650 code indicates a malfunction in the control circuit of the Malfunction Indicator Lamp (MIL), commonly known as the Check Engine Light. The powertrain control module (PCM) monitors the MIL circuit for proper voltage and continuity. When the PCM detects an open, short, or excessive resistance in the circuit, it sets this code. This can prevent the MIL from illuminating when a fault is detected, potentially hiding other issues.
1. Most Common Causes
- Blown fuse for the MIL circuit
- Faulty MIL bulb or LED
- Damaged wiring or connector in the MIL circuit
- Faulty instrument cluster
- Faulty PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light does not illuminate when key is turned on
- Check Engine Light stays on constantly
- Other warning lights may malfunction
- Vehicle may fail emissions test due to non-functional MIL
3. Step-by-Step Diagnosis
Step 1: Check the MIL fuse in the fuse box and replace if blown.
Step 2: Inspect the MIL bulb or LED for damage; replace if necessary.
Step 3: Visually inspect wiring and connectors for corrosion, breaks, or loose connections.
Step 4: Use a multimeter to test continuity and voltage at the MIL circuit.
Step 5: If all else is fine, test the instrument cluster or PCM for faults.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, the vehicle is generally safe to drive, but you may not be alerted to other engine problems. It's recommended to fix it promptly to ensure the MIL functions properly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, depending on the cause. A blown fuse or bulb is cheap, while instrument cluster or PCM replacement can be more expensive.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.