U0626 indicates that the control module responsible for climate control has lost serial communication with the A/C refrigerant pressure sensor. The sensor typically communicates over a LIN or low-speed CAN bus, and the code sets when messages are missing or corrupted for a calibrated period.
Internal sensor electronics or LIN/CAN transceiver fail, preventing it from transmitting pressure data.
Damaged wiring, corroded connector terminals, or a broken LIN/CAN wire between the sensor and the HVAC/PCM gateway.
Blown fuse, faulty relay, or corroded ground connection starves the sensor of its supply voltage.
The module that polls the sensor has a damaged communication driver or internal logic error.
Another node on the same LIN/CAN bus is holding the line dominant, blocking the sensor's transmissions.
Only plausible if multiple unrelated U-codes are present and bus diagnostics confirm the PCM's transceiver is defective.
Almost never. U0626 is a loss of communication with a specific sensor; the PCM is only the gateway in some architectures. Replace the PCM only after bus diagnostics prove its transceiver is at fault and all other causes are eliminated.
No. Low refrigerant affects pressure readings but does not cause a communication loss code. U0626 means the module cannot talk to the sensor at all.
Yes, drivability is unaffected. The only impact is loss of A/C function and possibly default defrost operation.
Because the sensor's messages are not reaching the module; the PID will remain blank or show a default value until communication is restored.