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U0605 Lost Communication With A/C Refrigerant Sensor A

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Open or shorted LIN, supply or ground wire to the sensor
Refrigerant sensor electronics failed
Electric compressor shorted internally, high-voltage A/C fuse open (Mazda PHEV)

Symptoms

  • A/C does not cool
  • Compressor switched off by the controller

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,500
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

ac refrigerant sensor aac compressor modulesensor wiring

Related codes

U0626U0627P0530P0D6D

References: static.nhtsa.gov, en.wikipedia.org.