P0D77 code meaning
A/C Compressor Control Module Output Driver Temperature Sensor Circuit High
Powertrain system Generic code P0Dxx codes Check engine light
What P0D77 means
P0D77 is the high-signal circuit code of the output driver (IGBT) temperature sensor in the electric A/C compressor. As with an NTC sensor, the high signal shows up as an impossibly cold temperature: GM sets it when the IGBT reading is at or below −40 °C, in all Volt and ELR tables from 2011 to 2019. The first-generation Volt needs 30 of 60 samples at 50 ms and evaluates only with outside air above −7 °C; the 2016 Volt counts 40 of 50 samples at 100 ms, the 2019 Volt 4 of 5 s, with the compressor reporting the fault over GMLAN. Type B, MIL after two trips. Without a valid power-stage temperature the compressor cannot protect itself and is normally switched off. Likely an open sensor path on the inverter board; hot-side code P0D78.
P0D77 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor1 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0D77
- Check engine light after two trips
- Air conditioning switched off
Common causes of P0D77
- Most likelyOpen circuit in the IGBT temperature sensor path
- PossibleCracked solder joint on the inverter board
- Less likelyFaulty value transmission to the host controller
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ac compressor cm output driver temp sensorAc compressor module
What each part of P0D77 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 77 | The exact fault in that area. |
What to do next
- Note P0D77 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 P0D77
What does P0D77 mean?
P0D77 means "A/C Compressor Control Module Output Driver Temperature Sensor Circuit High". P0D77 is the high-signal circuit code of the output driver (IGBT) temperature sensor in the electric A/C compressor. It is a generic code, so it means the same on every make.
Is it safe to drive with P0D77?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0D77 fail an emissions test?
P0D77 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 P0D77 to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0D77 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.