High Pressure Sensor / Switch: Service and Repair

High Pressure Sensor (G65)

• Vehicles with automatically regulated A/C system: Climatronic Control Module (J255) evaluates the signal from high pressure sensor and actuates the compressor via the A/C Compressor Regulator Valve (N280).

• Vehicles with manually regulated A/C system: A/C Control Module (J301) evaluates the signal from high pressure sensor and actuates the compressor via the A/C Compressor Regulator Valve (N280).

• Depending on the version of the high pressure sensor, an insufficient measuring value for the pressure in the refrigerant system will be sent by the high pressure sensor at low outside temperatures (lower than 5 °C) (even though the A/C system is OK and the refrigerant circuit is properly filled). In the A/C control module or in the Climatronic control module, part number 8P0 820 043 up to index AH can register an incorrect DTC memory entry at low outside temperatures (lower than 5 °C) (DTC memory entry: high pressure sensor "lower values not met"). The outside conditions, at which the fault was store, are displayed in the measuring value block for the automatic A/C system. Check using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function. If the fault is displayed as a sporadic fault at an outside temperature greater than 5 °C, calculated by the A/C system, and if the A/C function is OK, then clear the DTC memory (no additional steps are necessary).

• The cooling output cannot be checked with high pressure sensor removed, Climatronic control module / A/C control module does not switch on the A/C compressor.

• The refrigerant circuit remains closed, connection with valve.

• Checking function of high pressure sensor and signal sent. Refer to => [ High Pressure Sensor (G65), Checking Pressure Signal ] Testing and Inspection.

• Different component locations depending on engine, high pressure sensor in vehicles with 2.0 L Diesel engine is installed not on refrigerant line from expansion valve to condenser but rather on refrigerant line from compressor to condenser

• After switching off the A/C compressor in this vehicle, it may take a relatively long time for the pressure on the high pressure side to decrease. This is because the expansion valve is cold and the pressure on the low pressure side increases quickly after shutting the compressor off, then the expansion valve closes and the refrigerant flows slowly to the low pressure side.

- Remove the noise insulation.

- Disconnect connector - A - from high pressure sensor - B -.






• Depending on the engine, remove the high pressure sensor, the ribbed belt from the generator (for example, on the 2.0L TFSI engine).

- Remove high pressure sensor - B - (tightening specification: 8 Nm).

- Replace O-ring - C -. Refer to=> [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-Rings (allocation, refer to Electronic Parts Catalog).