P0650 Code: Malfunction Indicator Light (MIL) Control Circuit

The Malfunction Indicator Light (the words “Check Engine,” “Service Engine Soon” or the ISO symbol for the Malfunction Indicator (see image below) is an output to the instrument cluster from the ECM/PCM. Like all the other outputs, the computer sets a DTC when this output is malfunctioning. But for obvious reasons, you may not know the MIL isn’t functioning unless your vehicle develops some other concern that causes you to retrieve the DTCs with a scan tool.

NOTE: The MIL is typically related to Emissions Systems issues rather than low coolant or oil issues, so understanding what the light means is important.

The P0650 code is one of the trouble codes related to an issue with the check engine light or its circuit.

What Does the P0650 Code Mean?

To put it simply, code P0650 means that your MIL is not working as it should.

Typically, the MIL receives power from a fuse that also feeds the other indicator lights, and a ground from the ECM/PCM illuminates the light. When the light isn’t illuminated, the 12 volts feeding the B+ side of the lamp will pass all the way through the lamp filament to the ECM/PCM, and the computer’s algorithm is designed to watch this voltage.

Okay, so, the ECM/PCM knows when it has illuminated the MIL by grounding this circuit, so it also knows when it should and shouldn’t see that 12 volts. If the light isn’t commanded on but the ECM/PCM doesn’t see the 12 volts, the algorithm is written to store this DTC.

Diagnostic trouble code (DTC) P0650 stands for “Malfunction Indicator Light (MIL) Control Circuit.” It means that the ECM/PCM has detected a problem with that circuit. If the circuit is shorted to ground or chewed in two by a critter, the ECM/PCM won’t see the expected 12 volts when it hasn’t supplied the ground and the computer will set the P0650.

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Pro Tip: If the bulb is blown or the instrument cluster circuits are damaged, the ECM/PCM will recognize the absence of that 12 volts that should be coming from the bulb when it’s not illuminated, and that’ll set the code, too.

A self-test ideally occurs every time you start your vehicle. If you notice, once you insert your key and turn on the ignition, the MIL light normally illuminates for about 1-3 seconds before it goes out. During this time, the PCM checks the performance of the MIL circuit as described above.

Once your PCM detects an irregularity in voltage readings (too high, too low, no voltage), it will trigger the engine code P0650.

Note: The definition of each code may vary depending on the vehicle manufacturer. We recommend checking your trusted repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0650 Code?

There are several reasons why your scan tool may read a P0650 code. Here are some of the possible triggers of the code:

• Burnt out MIL bulb
• MIL circuit problems, such as damaged wiring or poor connections.
• Faulty PCM (rare cases)
• Failing instrument cluster

What are the Common Symptoms of the P0650 Code?

Although the error code P0650 does not cause any driveability problems, it is best to have your vehicle serviced right away once your scanner reads this code. Other faults in your engine may go undetected because of a faulty MIL.

Here are two of the common symptoms you should watch for:

• MIL not turning on when it should
• MIL turned on all the time

How to Diagnose the P0650 Code

Although this is a generic code, keep in mind that the diagnostic steps may vary depending on your vehicle’s year, make, and model. If you’re not well-versed with auto repair, it is best to let an experienced professional do the job for you.

However, if you are confident with your DIY auto repair skills and you want to diagnose this code yourself, feel free to diagnose it. Here is a video you can watch to help you understand the code better:

How to Fix the P0650 Code

There is no universal fix for a P0650 code. Repair steps may vary depending on your vehicle’s year, make, and model. For example, repair steps for a P0650 in a Nissan Altima may vary from a P0650 in a Kia Rio.

If you’re not a skilled automotive DIYer, the best course of action is to take your vehicle to an auto repair shop for proper diagnosis and repair. On the other hand, if you’re well-versed with auto repair, you may fix the error yourself.

You can use online auto repair manuals and guides to help you identify the repair steps that are applicable to your vehicle. You may also get an ALLDATA single-vehicle subscription to help you with your repair.

Products Mentioned in this Guide

Instrument Cluster Engine Control Module