U0605 code meaning
Lost Communication With A/C Refrigerant Sensor A
What U0605 means
The air conditioning controller needs refrigerant pressure or temperature to run the compressor and protect the circuit. Where this information comes over a serial link such as LIN, a single master polls the slave and expects an answer in a fixed schedule; U0605 means refrigerant sensor A no longer answers properly. Mazda shows a broader use: for the 2025 CX-70 and CX-90 plug-in hybrids, bulletin 07-002-26b assigns U0605 in the PCM to a LIN communication error between the electric A/C compressor and the PCM, often with P0D6D after an internal compressor short has blown the high-voltage A/C fuse; the fix is an updated compressor. U0626 and U0627 name dedicated pressure and temperature sensors. Usually the A/C stops cooling.
U0605 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0605
- A/C does not cool
- Compressor switched off by the controller
Common causes of U0605
- Most likelyOpen or shorted LIN, supply or ground wire to the sensor
- PossibleRefrigerant sensor electronics failed
- PossibleElectric compressor shorted internally, high-voltage A/C fuse open (Mazda PHEV)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ac refrigerant sensor aAc compressor moduleSensor wiring
What each part of U0605 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 05 | The exact fault in that area. |
What to do next
- Note U0605 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 U0605
What does U0605 mean?
U0605 means "Lost Communication With A/C Refrigerant Sensor A". The air conditioning controller needs refrigerant pressure or temperature to run the compressor and protect the circuit. It is a generic code, so it means the same on every make.
Is it safe to drive with U0605?
U0605 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0605 fail an emissions test?
U0605 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 U0605 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U0605 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.