Network, generic

U0626 Lost Communication With A/C Refrigerant Pressure Sensor A

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modeNo

Without a refrigerant pressure reading the climate controller cannot protect the compressor or schedule the condenser fan. When pressure sensor A digitizes its value itself and transmits it as a LIN or SENT frame, U0626 marks that the frame has stopped arriving; which point of the circuit gets the letter A is up to the manufacturer. No manufacturer documents U0626 publicly. Audi illustrates the pattern with its combined sensor G395, which the body module polls as a LIN slave: if the air quality sensor drops out together with it, the shared LIN wire is usually pinched (Audi stores its own codes). The A/C normally shuts down until contact returns. Hardwired sensors report P0530 to P0533 instead, and P2CD4 compares sensor A with B.

Likely causes

LIN wire to the sensor pinched, chafed or cut (Audi documents this for G395)

Corroded, loose or pushed-back terminals at the sensor connector

Sensor supply voltage missing or ground intermittently open

Sensor electronics failed, often after moisture or refrigerant leaking at the sensor

Symptoms

A/C compressor stays off, no cooling
A/C fault message or flashing A/C indicator
Other LIN devices on the same line may also report no communication

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–450

Time0.5–2.5 h

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

Parts involved

ac refrigerant pressure sensor avehicle bus wiring

References: static.nhtsa.gov, archive.r744.com, law.cornell.edu.