DTC:

U02A2-00

GDC18-059

Bulletin:

August 10, 2018

Date:
Description:
Applies to:

Lost Communication with Reductant Quality
Module – No additional information
US13 - US Emissions

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General Information
These repair instructions are intended to address the following fault(s):
DTC

Description

U02A2-00

Lost Communication
with Reductant Quality
Module

Possible
(Observable)
Symptoms

Possible Cause
x
x
x

The electronic control unit (ECU) has a software fault
or the wrong software version
Control unit has no supply voltage
Connector

None

Required Parts
Part Number

Description

Quantity

22021891

DEF Level Sensor (Tank 70 liter)

1

22021889

DEF Level Sensor (Tank 45 liter)

1

22021887

DEF Level Sensor (Tank 33 liter)

1

22015702

DEF Level Sensor (Tank 25 liter)

1

Repair Instructions
Aftertreatment Diesel Exhaust Fluid (DEF) Tank, Level Sensor, Replacement22306793

Removal
1. Secure the vehicle for service by parking it on a flat level surface, applying the parking brake, chocking the
rear wheels, and placing the transmission in neutral or park.
2. If equipped, remove the left-side fairing under the cab door to gain access to the diesel exhaust fluid (DEF)
tank and surrounding components.
3. Disconnect all cables from the negative (ground) battery terminals to prevent personal injury from electrical
shock and prevent damage to electrical components.
4. Connect the coolant extractor to the drain fitting at the bottom of the radiator and drain the coolant. Note: An
alternate method is to connect a coolant drain hose to the radiator drain fitting and drain the coolant into a
suitable container. Special tools: 85112740

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 1/8

DTC:

U02A2-00

Bulletin:
Date:

GDC18-059
August 10, 2018

5. Remove the drain plug from the DEF tank and, using a suitable container, catch any drained fluid remaining in
the tank. When all the fluid has drained, replace the drain plug and tighten.

1.
DEF Tank Drain Plug
6. Disconnect the electrical harness from the aftertreatment control module (ACM) electrical connector.

1. ACM Electrical Connector
7. If equipped, disconnect the electrical harness from the level sensor electrical connector.

1. Level Sensor Electrical Connector

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 2/8

DTC:

U02A2-00

Bulletin:
Date:

GDC18-059
August 10, 2018

8. If equipped, disconnect the electrical harness from the DEF quality sensor module electrical connector.
Remove the fasteners from the module.

1. DEF Quality Sensor Module Electrical Connector

1. DEF Quality Sensor Module Electrical Connector 25L Tank

1. DEF Quality Sensor Module Electrical Connector 33L Tank
9.
10.
11.
12.

Disconnect the electrical harness from the DEF pump electrical connector.
Disconnect the DEF pump-to-doser valve fluid hose and the electrical connector.
Disconnect the coolant lines from the DEF tank.
Position a floor jack under the DEF tank and use the jack to support the weight of the DEF tank.

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 3/8

DTC:

U02A2-00

Bulletin:
Date:

GDC18-059
August 10, 2018

13. Remove the fasteners securing the DEF tank to the frame-mounted brackets. The support pins at the bottom
of the brackets will hold the tank in place.

1. DEF Tank Mounting Fasteners
14. Using the floor jack, lift the DEF tank off the support pins on the two brackets and remove the DEF tank.

1. DEF Fluid Tank
15. Remove the DEF fluid hoses attached to the level sensor on the DEF tank. Note: Before detaching the DEF
fluid hoses, note their position since the hoses differ in size.

1. DEF Fluid Hose (Large & Small)
2. DEF Coolant Line (2)

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 4/8

DTC:

U02A2-00

Bulletin:
Date:

GDC18-059
August 10, 2018

16. Remove the two coolant lines attached to the level sensor on the DEF tank.
17. Loosen the clamp securing the level sensor to the DEF tank and remove the level sensor and quality sensor
module, if equipped. Use care when handling the sensor to avoid damaging the sensor.

1. Level Sensor
2. Clamp
Installation
1. Position the level sensor onto the DEF tank and tighten the clamp to secure it in place. Use care when
handling the sensor to avoid damaging the sensor.

1. Level Sensor
2. Clamp

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 5/8

DTC:

U02A2-00

Bulletin:
Date:

GDC18-059
August 10, 2018

2. Attach the two coolant lines to the fittings on the level sensor.

1. DEF Fluid Hose (2)
2. DEF Coolant Line (2)
3. Attach the two DEF fluid hoses to the fittings on the level sensor. Since the hoses are different sizes, be sure
to attach them to the correct fittings.
4. Using a floor jack, move the DEF tank and lift it into place on the support pins on the two frame-mounted
brackets. Loosely install the bolts and fasteners to attach the tank to the brackets, then lower and move the
floor jack out of the way.

1. DEF Fluid Tank
5. Tighten the DEF tank mounting fasteners and tighten to specification. Refer to Function Group 20,
Specifications.
6. Connect the two coolant lines to the fittings on the DEF tank.
7. Connect the DEF pump to doser valve fluid hose and the electrical connector.
8. Connect the electrical harness to the DEF pump electrical connector and secure with plastic tie straps as
needed.

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 6/8

DTC:

U02A2-00

Bulletin:
Date:

GDC18-059
August 10, 2018

9. Connect the electrical harness to the ACM electrical connector.

1. ACM Electrical Connector
10. If equipped, connect the electrical harness to the level sensor electrical connector.

1. Level Sensor Electrical Connector
11. If equipped, position the DEF quality sensor module and install fasteners. Connect electrical harness to the
DEF quality sensor module electrical connector.

1. DEF Quality Sensor Module Electrical Connector

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 7/8

DTC:

U02A2-00

Bulletin:
Date:

GDC18-059
August 10, 2018

1. DEF Quality Sensor Module Electrical Connector 25L Tank

1. DEF Quality Sensor Module Electrical Connector 33L Tank
12. Fill the DEF tank with DEF fluid.
13. Fill the cooling system with the recommended coolant using the coolant extractor. Special tools: 85112740
14. Connect all previously removed cables to the negative (ground) battery terminals. Tighten to 20 ±2 Nm (15
±1.5 ft-lb).
15. Start the engine and check for leaks and proper operation. Replenish fluids as needed.
16. Use Tech Tool to check and clear any diagnostic trouble codes (DTC).
17. If equipped, re-install the left-side fairing under the cab door.
Additional Resources
These repairs are the most likely fix for the identified fault(s), if this does not fix the issue, Tech Tool will need to be
used for more detailed diagnostics. If filing a warranty claim, please include the ASIST case number.
Labor Code
2589-03-02-05
Causal Part

0.6 - 2.0 (Depending on model)

22021891 (Tank 70 Liter)
22021889 (Tank 45 Liter)
22021887 (Tank 33 Liter)
22015702 (Tank 25 Liter)

© 2016 Mack Trucks, Inc. Information is subject to change without notice.

Page 8/8

DTC:

U02A2-00

Boletín:
Fecha:

Descripción: