JCB Tier 4 K0122 Boost Pressure Sensor Voltage Above Normal or Open Circuit

This instruction show you guide on how to repair JCB stage V Tier 4 Boost pressure sensor voltage above normal or open circuitĀ problem.

JCB Tier 4 K0122 Boost Pressure Sensor Voltage Above Normal or Open Circuit

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The measured boost pressure signal is above the normal operating range (> 4,9 V).


Possible causes are:

The boost pressure sensor wiring is defective. (Shorted to high source or an open circuit.)

The boost pressure sensor power supply is not correct.

The boost pressure sensor is defective.


Reaction in EEM

The FC is stored and the warning lamp is activated. Engine power will be reduced (Degradation Level 1). The CAN message indicates active fault. The engine functions dependent on the boost pressure are not active.



First save the error log and then erase it. Restart the ECU after erasing the error log. If the fault occurs again during the next driving cycle, check the following paths:

Check the boost pressure sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).

Check the 5 V power supply to the sensor.

Check the operation with another boost pressure sensor to see if the boost pressure sensor is defective.

More repair case for JCB,please refer to:JCB Trouble Repair



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