U0626: Lost Communication With A/C Refrigerant Pressure Sensor A

What it means

A control module has stopped receiving expected network messages from A/C refrigerant pressure sensor A. The effect on A/C operation depends on the vehicle's system design.

How it works

A/C refrigerant pressure sensor A reports pressure information to other vehicle modules over the network. The receiving module monitors for the sensor's expected messages, and U0626 sets when they are missing. The A/C system may limit or disable operation to protect itself.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• A/C may not operate as intended
• Warning light or message related to the A/C system

How to diagnose it

1. Scan all modules and save available freeze-frame or event data to determine whether the fault is isolated to pressure sensor A or part of a wider network problem.
2. Check A/C live data for pressure sensor A and note whether its value is absent while other A/C data remains available.
3. Inspect sensor A's connector and nearby network wiring for loose pins, corrosion, chafing, or impact damage.
4. Check the sensor module's power and ground against the manufacturer's specification.
5. Test the network wires to sensor A for opens or shorts using the vehicle wiring diagram and the manufacturer's procedure.

Common fixes

• Clean and secure sensor A's connector or repair its damaged wiring.
• Restore the sensor module's power or ground.
• Repair an open or short in the communication wiring to pressure sensor A.
• Replace the sensor module if its wiring, power, and ground are correct but it still does not communicate.

Can I keep driving?

Driving is generally unaffected, but the A/C may not cool or may be disabled. Avoid relying on the A/C for demisting until it works correctly.