Electronic Control Unit (ECU) Power Supply Voltage Too High or Too Low
The ECU is detecting power supply voltage levels outside of normal operating range.
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)
Inside the ECU, voltage levels from the battery or generator should be between 9V-16V. If it goes above 16V or below 9V, the ECU throws this code to warn you that it might not function properly.
What the computer is actually seeing
The ECU monitors its own supply voltage and sends this data to the internal system checks. If the voltage strays outside of the 9V-16V range, it logs a fault.
What a healthy reading looks like
Normal voltage supply should be between 9 volts and 16 volts. Anything above or below this triggers the fault code.
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. Check battery voltage with a multimeter; it should be between 12.4V-12.7V (engine off) and 13.7V-14.7V (engine running). Decision: Is voltage within range?
- 22. Inspect all wiring and connectors to the ECU and battery for corrosion or damage. Decision: Are all connections solid?
- 33. Test the alternator output; it should be around 13.5V-14.5V while engine is running. Decision: Is alternator functioning within spec?
- 44. Check for any additional fault codes that might indicate related systems failing. Decision: Are there other codes present?
Common causes
- Faulty alternator
- Weak battery
- Wiring issues (shorts or opens)
- ECU malfunction
- Poor ground connection
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive until voltage issues are resolved; it can lead to other electrical problems.
Will this code come back after clearing?
If the underlying issue is not fixed, the code will likely return.
Why does this code appear with other codes?
Voltage issues can affect multiple systems, causing related codes to be logged.
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