P2D42 code meaning
A/C Compressor Motor Voltage B Low
Powertrain system Generic code P2Dxx codes Check engine light
What P2D42 means
P2D42 is stored when voltage B at the electric A/C compressor motor stays below the lower limit of its working range, so the inverter cannot drive the motor properly and usually switches it off. Unlike a sensor circuit code, it refers to the voltage that is actually present. No manufacturer documents P2D42 on an official public source. Mazda's bulletin 07-002/26 for the CX-90 and CX-70 plug-in hybrids shows the classic cause on the voltage A side (P0D6D): an internal short blows the A/C high-voltage fuse. GM's 2011 Volt flagged a compressor input of 190 V or less as P0D6B. A loose high-voltage connector or open contactors also fit. The A/C stops cooling; plug-in hybrids may lose battery cooling too.
P2D42 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2D42
- A/C blows warm air
- Hybrid system warning, possibly reduced battery cooling or charging power
Common causes of P2D42
- Most likelyBlown A/C high-voltage fuse, often after an internal compressor short
- PossibleLoose or corroded high-voltage connector at the compressor
- PossibleInternal fault in the compressor inverter or measurement
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ac compressor motorAc compressor moduleWiring harness
What each part of P2D42 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 42 | The exact fault in that area. |
What to do next
- Note P2D42 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 P2D42
What does P2D42 mean?
P2D42 means "A/C Compressor Motor Voltage B Low". P2D42 is stored when voltage B at the electric A/C compressor motor stays below the lower limit of its working range, so the inverter cannot drive the motor properly and usually switches it off. It is a generic code, so it means the same on every make.
Is it safe to drive with P2D42?
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 P2D42 fail an emissions test?
P2D42 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 P2D42 to fix?
Difficulty: workshop only. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P2D42 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.