P0D77: 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. 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.

Symptoms

• Check engine light after two trips
• Air conditioning switched off

Most likely causes

• Open circuit in the IGBT temperature sensor path
• Cracked solder joint on the inverter board
• Faulty value transmission to the host controller

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the battery and grounds
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
3. Clear the code and see if it returns
4. If it is a reference voltage code, disconnect sensors one at a time and see if the voltage recovers
5. Check whether a software update is available
6. Do not replace the control module without a full diagnosis

What each character of P0D77 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• D: Subsystem depends on the code range
• 77: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0D77?

It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

What causes code P0D77?

The most common causes are: open circuit in the IGBT temperature sensor path; cracked solder joint on the inverter board; faulty value transmission to the host controller.

Related codes

• P0D78A/C Compressor Control Module Output Driver Temperature Sensor Circuit Low
• P0D76A/C Compressor Control Module Output Driver Temperature Sensor Performance
• P0D75A/C Compressor Control Module Output Driver Temperature Sensor Circuit
• P0D79A/C Compressor Control Module Output Driver Temperature Sensor Circuit Intermittent/Erratic
• P0D72A/C Compressor Control Module Internal Temperature Sensor A Circuit High

Sources

• gsi.ext.gm.com: 11OBDG01 HYBRID Diagnostics
• gsi.ext.gm.com: 16OBDG01 Hybrid Diagnostics
• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.