P0E66 code meaning
Battery Charger Control Circuit Low
What P0E66 means
With P0E66 the controller finds the charger command line pulled lower than the state it is driving, which typically means the wire touches ground somewhere between the control unit and the on-board charger. If the command is active-high, the charger simply never receives it; a grounded line can also overload the output stage that drives it. No manufacturer documents P0E66 publicly. GM's Volt and 2019 hybrid tables check this line only through the general code P0E65, based on a hardware fault flag sampled every 25 ms at 10.2 V or more. California's OBD rule requires plug-in hybrids to recognise charger faults that stop or limit charging. P0E67 is the opposite case, a line stuck high; P0E68 covers a line that is electrically sound but answers wrongly.
P0E66 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0E66
- Charging does not start after plugging in
- Charge indicator shows a fault or goes out
Common causes of P0E66
- Most likelyControl wire chafed through to body ground
- PossibleMoisture in a connector bridging the signal to ground
- Less likelyInternal short in the charger's command input
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Battery charger control circuitWiring harnessOn board charger
What each part of P0E66 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 66 | The exact fault in that area. |
What to do next
- Note P0E66 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0E66
What does P0E66 mean?
P0E66 means "Battery Charger Control Circuit Low". With P0E66 the controller finds the charger command line pulled lower than the state it is driving, which typically means the wire touches ground somewhere between the control unit and the on-board charger. It is a generic code, so it means the same on every make.
Is it safe to drive with P0E66?
P0E66 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0E66 fail an emissions test?
P0E66 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0E66 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P0E66 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.