Power Supply Voltage Too Low
The power supply voltage detected by the control module is below optimal levels.
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What it means (plain English)
The control module is seeing a voltage drop, often below 9 volts, which can cause it to malfunction. This might happen because of weak batteries, bad connections, or issues with the alternator.
What the computer is actually seeing
The control module monitors the battery voltage and expects to see values around 12.5 volts or higher when the engine is off and 13.5 to 14.5 volts when running. Anything below 9 volts can trigger this code.
What a healthy reading looks like
At rest: 12.5V to 12.8V, Engine running: 13.5V to 14.5V, Under load: should not drop below 9V.
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. Is it above 12.5 volts? If no, charge or replace the battery.
- 22. Inspect battery terminals and cables for corrosion or loose connections. Is everything clean and tight? If no, clean and secure connections.
- 33. Start the engine and recheck voltage. Is it between 13.5 and 14.5 volts? If no, suspect the alternator.
- 44. With the engine running, check for voltage drop across the battery terminals. Is it less than 0.5 volts? If no, repair or replace damaged battery cables.
- 55. Inspect ground connections from the control module to the battery. Are they secure and free of corrosion? If no, clean or replace as needed.
Common causes
- Weak or discharged battery
- Faulty alternator
- Corroded battery terminals
- Damaged wiring or connectors
- Bad ground connections on the battery or control modules
Typical repair cost
$100-$300
Related codes
Frequently asked questions
Is it safe to drive with this code?
Drivability might be affected, especially if the voltage drops too low, so it’s best to fix it soon.
Will this code come back if I clear it?
Yes, if the underlying issue isn't fixed, it will likely come back after a drive cycle.
Why does this code pair with SPN 6115?
SPN 6115 relates to battery voltage, so if one code is triggered, the other often follows due to interlinked electrical issues.
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