MCM Power Supply Voltage
The engine control module (ECM) is reporting a problem with the power supply voltage.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine control module isn't getting the right voltage it needs to work correctly. It should be receiving between 9 and 32 volts, and if it's outside this range, it can't perform accurately.
What the computer is actually seeing
The ECM monitors its own voltage supply. If the voltage drops below 9 volts or rises above 32 volts, it triggers this code.
What a healthy reading looks like
Expected voltage range is 9 to 32 volts from the power supply to the ECM.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the battery terminals and cables for corrosion or looseness. Clean and tighten as needed. Decision point: Is the battery connection good? Yes - Go to step 2. No - Handle battery connections and retest.
Common causes
- Weak battery or poor connections
- Faulty voltage regulator
- Damaged wiring harness or connectors
- Short circuit or open circuit in the power supply line
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not advisable to drive if this code persists, as it can lead to further electrical issues.
Will this code come back if I clear it?
Yes, if the underlying problem isn’t fixed, the code will likely return.
Why does this code appear with other faults?
Multiple faults may indicate a larger problem with the electrical system or ECM.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →