ECM Power Supply Voltage Low
The engine control module (ECM) is detecting a low voltage condition.
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 computer that controls the engine is seeing a voltage drop below what it needs to operate correctly, usually less than 10 volts.
What the computer is actually seeing
The ECM monitors its own power supply and when the voltage drops below 10 volts (normal is around 12-14 volts), it triggers this code.
What a healthy reading looks like
The ECM should receive between 11.5 to 14.5 volts when the engine is running.
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.
- 1Check the battery voltage with a multimeter; should be above 12.4 volts.
- 2Inspect battery terminals and cables for corrosion or loose connections, clean/reconnect as needed.
- 3Test the alternator output; it should be between 13.5 and 14.5 volts with the engine running.
- 4Check the wiring from the battery to the ECM for damage or shorts, especially in high heat areas.
- 5If all previous checks are good, consider checking or replacing the ECM.
Common causes
- Corroded battery terminals
- Weak battery
- Faulty alternator
- Wiring issues between battery and ECM
- Faulty ECM itself
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally drivable, but expect possible performance issues and pay attention to battery and electrical symptoms.
Will this code come back after clearing it?
If the underlying problem isn't fixed, it will likely return after clearing.
Why does this relate to my battery?
The ECM relies on stable voltage from the battery for proper operation, and low voltage can cause erratic behavior.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
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