P0D66 code meaning
Hybrid/EV Battery Pack Cooling Fan Enable Circuit High
Powertrain system Generic code P0Dxx codes Check engine light
What P0D66 means
P0D66 stands for a short to voltage on the enable output of the battery cooling fan. Because the line is pulled high from outside, the fan may run although the controller wants it off, or the controller simply loses authority over it. GM's 2013 eAssist table 13OBDG05C flags it through the output driver's fault status, 20 failures in 25 samples at 250 ms, Type B. In the hybrid tables 16OBDG02 to 19OBDG02 the check runs with the enable commanded off: 5.27 to 19.7 V on the output at system voltage above 10.2 V counts as a failure, 16 in 20 samples set the code, Type B, MIL after two trips. Look for the enable wire rubbing against a supply wire or water in the connector. A fan that never stops drains the 12 V battery. Open circuit is P0D64, short to ground P0D65.
P0D66 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0D66
- Check engine light or hybrid warning after two trips
- Battery cooling fan runs continuously, even with the vehicle off
- Discharged 12 V battery after standing
Common causes of P0D66
- Most likelyEnable wire rubbed through and touching a 12 V supply wire
- PossibleMoisture in the fan connector bridging enable and supply pins
- Less likelyInternal fault in the fan electronics feeding voltage back onto the enable line
- Less likelyEnable driver in the battery controller defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery cooling fan enableWiring harnessBms
What each part of P0D66 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 P0D66 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 P0D66
What does P0D66 mean?
P0D66 means "Hybrid/EV Battery Pack Cooling Fan Enable Circuit High". P0D66 stands for a short to voltage on the enable output of the battery cooling fan. It is a generic code, so it means the same on every make.
Is it safe to drive with P0D66?
Drive gently and only to a workshop. With P0D66 the car can go into limp mode (reduced power) to protect itself.
Will P0D66 fail an emissions test?
Yes, it can. P0D66 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0D66 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0D66 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.