How to Erase P0654: Malfunction Indicator Lamp (MIL) Control Circuit Malfunction

As a car owner, encountering the Malfunction Indicator Lamp (MIL) can be unsettling. The MIL, also known as the check engine light, is a warning signal from your vehicle’s onboard diagnostics system. When the MIL illuminates, it indicates the presence of a potential issue with your vehicle.

One of the codes associated with the MIL is the P0654 code, which specifically points to a malfunction in the MIL control circuit. In this article, we will explore how to address the P0654 code, providing you with step-by-step instructions and helpful tips to resolve the issue.

Understanding the P0654 Code:

The P0654 code refers to a malfunction in the control circuit of the Malfunction Indicator Lamp (MIL).

The MIL control circuit is responsible for activating the check engine light when an issue is detected by the vehicle’s onboard diagnostics system.

car vertical

A malfunction in this circuit can prevent the proper functioning of the MIL, leading to the illumination of the check engine light or its failure to illuminate when necessary. Several factors can contribute to the P0654 code, including damaged wiring, faulty connectors, or issues with the Powertrain Control Module (PCM).

Diagnostic Process:

Before proceeding with troubleshooting and fixing the P0654 code, it is important to gather the necessary tools and equipment.

You may need a code reader or scanner, a digital multimeter, and a vehicle repair manual specific to your car model. Once prepared, you can begin the diagnostic process by identifying the affected vehicle components.

The MIL control circuit is typically connected to the PCM and various sensors. Locate these components and visually inspect them for any visible signs of damage or loose connections.

Troubleshooting Steps:

To address the P0654 code and fix the MIL control circuit malfunction, follow these troubleshooting steps:

Step 1: Inspecting the wiring harness and connectors – Examine the wiring harness and connectors associated with the MIL control circuit. Look for any signs of damage, such as frayed wires or corrosion. Ensure that the connectors are securely plugged in.

Step 2: Testing the MIL control circuit voltage – Use a digital multimeter to measure the voltage in the MIL control circuit. Compare the readings to the specifications provided in your vehicle repair manual. Any significant deviations from the specified range may indicate an issue.

Step 3: Checking the PCM (Powertrain Control Module) – Inspect the PCM for signs of damage or malfunction. The PCM is responsible for controlling various aspects of the vehicle’s performance, including the MIL control circuit. If the PCM is faulty, it may need to be repaired or replaced.

Step 4: Verifying the ground connections – Ensure that all ground connections related to the MIL control circuit are clean and properly secured. Loose or corroded ground connections can interfere with the circuit’s functionality.

Fixing the P0654 Code:

To fix the P0654 code and restore the proper functioning of the MIL control circuit, follow these steps:

Step 1: Repairing or replacing damaged wiring or connectors – If you identified any damaged wiring or connectors during the inspection, repair or replace them as necessary. Ensure proper insulation and secure connections.

Step 2: Repairing or replacing faulty PCM or other affected components – If the PCM or any other components related to the MIL control circuit are faulty, consider repairing or replacing them. Consult with a professional mechanic or refer to your vehicle repair manual for guidance.

Step 3: Verifying proper functioning of the MIL control circuit – After performing the necessary repairs, retest the MIL control circuit using a digital multimeter. Ensure that the voltage readings are within the specified range. If everything is functioning correctly, the P0654 code should no longer be present, and the check engine light should behave as expected.

Preventive Measures:

To minimize the occurrence of the P0654 code or any other issues related to the MIL control circuit, consider the following preventive measures:

  1. Regular vehicle maintenance – Follow the recommended maintenance schedule for your vehicle, including oil changes, filter replacements, and system inspections. Routine maintenance helps identify and address potential problems before they escalate.
  2. Keeping an eye on warning lights and codes – Pay attention to warning lights, including the MIL. If the check engine light illuminates, promptly diagnose the issue using a code reader or scanner. Addressing the underlying problem early can prevent further complications.


Dealing with the P0654 code and a malfunctioning MIL control circuit can be frustrating. However, by following the diagnostic process and troubleshooting steps outlined in this article, you can effectively address the issue. Remember to gather the necessary tools, inspect the wiring and connectors, test the voltage, and repair or replace any damaged components. Regular vehicle maintenance and attentive monitoring of warning lights will help prevent such issues in the future.


Q: Can I continue driving my vehicle with the P0654 code?

  1. A: It is generally recommended to address the underlying issue causing the P0654 code as soon as possible. Continuing to drive the vehicle without resolving the problem may result in further damage or decreased performance.

Q: Can I erase the P0654 code without fixing the issue?

  1. A: While you can temporarily erase the code using a code reader or scanner, it will likely reappear if the underlying problem is not resolved. It is essential to diagnose and fix the root cause to prevent ongoing issues.

Q: Can I fix the MIL control circuit malfunction myself, or do I need professional assistance?

  1. A: Depending on your mechanical expertise and access to tools, you may be able to address the issue yourself. However, if you are unsure or uncomfortable with the diagnostic and repair process, it is recommended to seek professional assistance from a qualified mechanic.