P0D79 code meaning
A/C Compressor Control Module Output Driver Temperature Sensor Circuit Intermittent/Erratic
What P0D79 means
P0D79 marks an erratic signal from the output driver temperature sensor, the sensor that guards the compressor's power transistors: values flicker or drop out briefly instead of staying wrong. No manufacturer publishes set criteria. GM's 2019 Volt table lists P0D79 next to P0D77 and P0D78 as an IGBT-sensor circuit fault that suspends the plausibility checks, which shows the code is in use, but without thresholds. A Hyundai patent on temperature sensors for power switches names loose connectors, electrical noise, board defects and cold solder joints as typical origins of such unstable readings. Because the compressor can no longer trust its overheat protection, it may cut out repeatedly. CARB requires thermal-management inputs to be checked for circuit faults.
P0D79 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0D79
- Air conditioning cuts out repeatedly
- Code appears sporadically
Common causes of P0D79
- PossibleCold or cracked solder joint at the IGBT sensor
- PossibleLoose low-voltage connector or ground at the compressor
- Less likelySwitching noise from the inverter coupling into the sensor signal
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 P0D79 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 79 | The exact fault in that area. |
What to do next
- Note P0D79 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 P0D79
What does P0D79 mean?
P0D79 means "A/C Compressor Control Module Output Driver Temperature Sensor Circuit Intermittent/Erratic". P0D79 marks an erratic signal from the output driver temperature sensor, the sensor that guards the compressor's power transistors: values flicker or drop out briefly instead of staying wrong. It is a generic code, so it means the same on every make.
Is it safe to drive with P0D79?
P0D79 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0D79 fail an emissions test?
P0D79 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 P0D79 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will P0D79 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.