High Pressure Sensor (G65), Checking Pressure Signal

High Pressure Sensor (G65), Checking Pressure Signal

Special tools, testers and auxiliary items required

• Assembly Tool (T10118)

• The cooling output cannot be checked when the high pressure sensor is removed. The Climatronic control module (J255) will not switch on the A/C compressor. Refer to Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding".

• 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.

• 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). At lower outside temperatures (ambient temperature lower than 5 °C), A/C System control heads-the Climatronic control module with part number "8J0 820 043" through to index "AJ"-might therefore make an incorrect DTC memory entry (DTC memory entry: high pressure sensor ", and fall below the lower threshold"). 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). This error does not occur with -the Climatronic control module, part number "8J0 820 043" beginning with index "AK".

Test Sequence






The High Pressure Sensor (G65) - item B - is at the right on the bottom of the condenser.

- Disconnect electrical connector - A -.

Routing 3-pin connector on High Pressure Sensor (G65)

1. Ground

2. Signal output - Square wave signal to Climatronic control module (J255)

3. Terminal 75 (positive)


• With electrical connector - A - disconnected, the A/C compressor is not switched on.

• The high pressure sensor (G65) - B - is an electronic control module, which creates a square wave signal, the duty cycle ratio changes with pressure in the refrigerant circuit. Refer to => [ High Pressure Sensor (G65) Signal ] Description and Operation.

• Pressure signal from the high pressure sensor, refer to=> [ High Pressure Sensor (G65) Signal ] Description and Operation.