P0650 DTC Code: Definition, Causes, and Diagnostic Process


In the world of automotive diagnostics, trouble codes play a crucial role in identifying and resolving issues within a vehicle’s systems. One such trouble code is the P0650 DTC code. If you’ve encountered this code, it indicates a malfunction in the “Malfunction Indicator Lamp (MIL)” control circuit.

This article aims to provide you with a comprehensive understanding of the P0650 DTC code, including its definition, potential causes, and the diagnostic process involved in addressing this issue.

Understanding the P0650 DTC Code


The P0650 DTC code is associated with the Malfunction Indicator Lamp (MIL) control circuit in a vehicle’s onboard diagnostic system. When this code is triggered, it signifies an issue with the circuit responsible for controlling the illumination of the “Check Engine” or “Service Engine Soon” light on the dashboard.


Several factors can lead to the activation of the P0650 DTC code. Here are some common causes:

  1. Faulty Bulb or LED: A commonly overlooked cause is a malfunctioning bulb or LED that indicates an issue with the MIL. In such cases, a simple replacement of the bulb or LED may resolve the problem.

  2. Wiring Issues: Faulty wiring connections, damaged wires, or loose connections may disrupt the proper functioning of the MIL control circuit. These issues should be inspected and repaired if necessary.

  3. Defective Powertrain Control Module (PCM): The PCM is responsible for controlling various vehicle systems, including the MIL. If the PCM itself is malfunctioning or has failed, it may trigger the P0650 code.

  4. Faulty MIL Control Circuit: Damage to the MIL control circuit due to moisture, corrosion, or electrical shorts can also lead to the activation of the P0650 DTC code. Inspection and repair of the affected circuit may be required.

Diagnostic Process

When faced with a P0650 DTC code, it is essential to follow a systematic diagnostic process to identify and resolve the underlying issue. Here’s a step-by-step guide on how to diagnose the problem:

Step 1: Initial Inspection

Begin by visually inspecting the MIL bulb or LED on the dashboard. Check if it illuminates when turning the ignition on. If it doesn’t, ensure that the bulb or LED is not burnt out or damaged. Replace it if necessary.

Step 2: Check Wiring Connections

Next, inspect the wiring connections related to the MIL control circuit. Look for loose, disconnected, or damaged wires. Repair any wiring issues found during this inspection, ensuring proper connections are made.

Step 3: Test the Powertrain Control Module (PCM)

Using a reliable diagnostic tool, scan the PCM for any other associated trouble codes. Analyze the data retrieved from the PCM to identify any potential problems affecting the MIL control circuit. Consider replacing the PCM if it is found to be defective.

Step 4: Investigate MIL Control Circuit

Focus on the MIL control circuit itself. Perform a thorough examination to identify any signs of damage, moisture intrusion, or electrical shorts. Address any issues found by repairing or replacing the affected parts as required.

Step 5: Clear the Trouble Codes

After performing the necessary repairs, clear the trouble codes from the vehicle’s system using the diagnostic tool. This step will ensure that the repaired circuit is functioning correctly, and the MIL control circuit is back to normal operation.

Frequently Asked Questions

Below are three frequently asked questions regarding the P0650 DTC code:

Q1: Can a faulty MIL control circuit affect the overall performance of the vehicle?

A1: No, a faulty MIL control circuit does not directly impact the performance or drivability of the vehicle. However, it is crucial to address this issue promptly as it may indicate deeper underlying problems within the vehicle’s systems.

Q2: Is it possible to mistakenly diagnose a P0650 code due to a burned-out bulb?

A2: Yes, a burnt-out MIL bulb can trigger the P0650 DTC code. It is essential to check the bulb or LED on the dashboard before proceeding with further diagnostic steps.

Q3: Can I resolve the P0650 code myself, or should I seek professional help?

A3: While you may be able to address simple causes of the P0650 code, such as a burnt-out bulb, complicated issues like a defective PCM or damaged wiring may require professional assistance. It is recommended to consult a qualified mechanic or technician for accurate diagnosis and repair.


The P0650 DTC code signifies a malfunction in the Malfunction Indicator Lamp (MIL) control circuit. Understanding the potential causes and following a systematic diagnostic process will help you resolve this issue effectively. Whether it’s a simple bulb replacement or more complex wiring repairs, addressing the P0650 DTC code promptly will enable you to maintain the optimal performance of your vehicle.

About author


Meet Sam Mitchell, your experienced and reliable guide in the complex world of car fault codes. With a robust career spanning over 15 years as a professional car mechanic, John has the skills, knowledge, and practical experience to help you navigate car fault issues with confidence.


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