P2508: Engine Control Module Power Input Signal High
What to do
Expect warning lights. If a charging system overvoltage fault is stored as well, that is the fault to fix — this code is reporting the same thing from the module's side. Overcharging damages the battery and the electronics for as long as the engine runs, so do not leave it.
What this code means
The module's monitored supply reads above its valid range.
The usual cause is upstream: a charging system overcharging, which is the fault described at P2504 and carries its own damage. Where a charging voltage high code is stored alongside this one, they are the same fault and the charging system is where the repair is.
Where charging is correct, a wiring fault feeding the monitoring input from the wrong source is the alternative, and that is a harness question rather than a module one.
Likely causes
Start here
- Faulty alternator voltage regulator · moderate
- Faulty alternator · moderate
Less common
- Wiring shorted to voltage · moderate
- Poor alternator or engine earth connection · moderate
Rare
- Faulty engine control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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