KC-2165

3/1/23, 11:19 AM
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Mack DEF Pump Troubleshooting Guide US10+OBD13 And Newer Emissions
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Component Overview
DEF Pump
The Diesel Exhaust Fluid (DEF) Pump's function is to build and regulate
the DEF systems pressure that is supplied to the dosing valve. The DEF
Pump is a multi-unit component that consists of:
Mechanical pump
Reverting valve
Pressure sensor
Main filter
Fluid connectors (2 coolant & 3 DEF)
Electrical connector
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The DEF Pump is controlled by the After-Treatment Control Module
(ACM). On every key cycle, the sensors and actuators in the DEF dosing
system perform a self-check for proper operation. When the truck is
turned off, the ACM uses a temperature based delayed reverting/draining
strategy to pump the DEF back into the tank.
The primary failure mode of the DEF Pump is:
Leak - externally leaking fluid
Internal Failure - which will generate a specific DTC
Diagnose and Repair
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NOTE: a large amount of DEF Pumps returned through warranty have
beenUItested and determined to have No Fault Found. It is extremely
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important to not replace the DEF Pump unnecessarily but to determine
the root cause of the failure.
Leaking DEF
Not all leaks at the DEF pump require replacement of the pump
assembly. It is imperative to determine the location of the leak.
1. Clean the suspected area using a suitable solvent.
2. Run PTT Option 2589-08-03-05 Subtest A to pressurize the system.
3. Inspect the affected area to determine the location of the leak using
the table below.
Location of Leak
Direction
Fluid Connectors
Repair or Replace fitting and/or hose
Filter Assembly
Replace Filter Assembly
Electrical Connector
Replace Pump and Harness
Pump splitting
Replace Pump
Internal Failure of the Pump
All internal pump failures will generate a specific Diagnostic Trouble
Code (DTC)
Perform a DTC Readout using Premium Tech Tool. Review the tables
below to determine which category the Fault Code currently being
diagnosed falls under. Proceed according to the directions for the
appropriate section.
Under Pressure Faults
DTC
Description
P20E8-92
Reductant Pressure Too Low, Incorrect Operation
P202D-00
Aftertreatment Reagent Pressure Leakage
P20BA-00
Reductant Heater A control Performance
Directions:
1. Inspect def tank for frozen fluid, debris, or low level.
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2. Disconnect the supple line at the DEF Pump.
3. Connect a clear 3/8" (inner diameter) hose to the fitting and place the
other end of the hose into the DEF Tank.
• Note: This will require removal of DEF Tank Filer Neck Insert
(Impact 2589-03-02-42).
4. Run Pressure Build Up Operation in PTT 2589-08-03-05 Selection A.
Ensure the DEF Pump is running (audible noise) and allow to run for at
least 5 minutes.
5. Evaluate results:
• If the system is not able to build pressure: Replace the inlet
fitting (which contains a screen, which could be blocked). Re-run
evaluate. If the pump is still not able to build pressure, Replace the
DEF Pump in accordance with Impact operation 2581-03-02-01 .
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• If the system is able to build pressure: The pump in not the
issue. Further diagnosis is needed for the supply side of the
system. Inspect the below components and repair as necessary:
- DEF Tank Vent - make sure the vent is clean and free of
debris.
○ NOTE: Do NOT blow air through the line, as this will
likely introduce debris into the DEF Tank.
- Lines Blockage from DEF Tank to Pump.
- Blocked/damaged Tank Screen or pickup tube.
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Over Pressure Faults - only diagnose active DTCs.
DTC
Description
P208B-00
Reductant Pump "A" Control Performance/Stuck Off
P10CE-97
Reductant Return No Flow Detected
P20A1-07
Aftertreatment Reagent Direction Valve Mechanical
Problem
Directions:
1. Inspect def tank for frozen fluid or debris.
2. Replace return line fitting (this fitting contains a return orifice).
3. Run Pressure Build Up Operation in PTT 2589-08-03-05 Selection A.
UI
4. Evaluate
the results
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• If the DEF Pump builds pressure and does not shut
down for 5 minutes: Clear the faults and release the
vehicle.
• If the DEF Pump over pressures and stops running
(DTC will log again):
a. Check return line (from DEF Pump to DEF Tank) for
blockage and replace as necessary.
b. Re-run the evaluation. If the pump continues to
overpressure, replace the pump in accordance with
Impact operation 2581-03-02-01.
Electrical Faults - only diagnose active or confirmed DTCs
DTC
Description
P20A0-13
Reductant Purge Control Valve, Open Circuit
P10AD-13
Reductant Pump "A" Control Low Side, Open Circuit
P204A-13
Reductant Pressure Sensor, Open Circuit
P208A-13
Reductant Pump "A" Control, Open Circuit
P208C-00
Aftertreatment Reagent Pump Control Short Circuit Low
P20A2-00
Aftertreatment Reagent Direction Valve Short Circuit Low
P204C-00
Aftertreatment Reagent Pressure Sensor Circuit Low
P10AF-00
Reductant Pump "A" Control Low Side Circuit High
P204B-64
Aftertreatment Reagent Pump Orifice Blocked
P10AE-00
Reductant Pump "A" Control Low Side Circuit Low
P208D-00
Aftertreatment Reagent Pump Control Short Circuit High
P20A3-00
Aftertreatment Reagent Direction Valve Short Circuit High
Directions: all of the above codes will cause the DEF Pump to
discontinue operation until code is corrected. Inspect electrical circuits
using PTT Diagnostics to identify the electrical issue.
NOTE: For trucks operating in a dirty or harsh environment and
experiencing repeat DEF Pump Failures see Technical Service Bulletin
(TSB) Aftertreatment Diesel Exhaust Fluid (DEF) Tank Vent Filter,
New Installation.
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Rules for Replacement
Warranty will only cover replacement of the DEF Pump if:
Leak is identified as unrepairable (leaks at fittings or main filter are
repairable), these pumps may require parts returned for analysis.
Fault codes in the Yellow sections above is active or confirmed.
In addition, if the DEF Pump is being replaced. Maintenance records will
be required showing the cleaning of the DEF Tank and Filter Change
have been properly maintained and are not the root cause of the failure.
Refer to Service At a Glance (SAG) found in the Trucks Dealer Portal
under the Information tab - Service - Service literature for replacement
and cleaning intervals of the DEF Tank & Filters.
Standard Diagnostic Time 1.0 hrs
Diagnostic Trouble Codes With DEF/Urea in the
Description
Direction/Repair: DO NOT REPLACE the DEF Pump for these codes.
Diagnostics should be performed using PTT Diagnostics and the comment
section in the table below.
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DTC
Description
Probable Source
P2042-
Reductant Temperature
Temperature - Check wiring
01
Sensor, Electrical Failure
harness CBR-2015
P21CA- Reductant Control Module
Check ACM Power Supply CBR-
00
Supply Voltage
2040
P204364
Aftertreatment Reagent Tank
Temperature Sensor Stuck,
Signal plausibility failure
TBD
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Tags
p2042-01
p20a3-00
def pump
def tank
def filter
p204b-64
p10af-00
p204c-00
p20a2-00
p208c-00
p208a-13
p10ce-97
p20a1-07
p20e8-92
p202d-00
p20ba-00
p204a-13
p10ad-13
p20a0-13
p208b-00
unlocking uptime
mack
p208d-00
p10ae-00
p21ca-00
p2043-64
Categories
Make and Model > Mack > CXU/CHU/PI - Pinnacle
Make and Model > Mack > LEU - TerraPro Low Entry
Make and Model > Mack > LR
Make and Model > Mack > TD - Titan
Make and Model > Mack > MRU/TE - TerraPro
Vehicle System > Emissions
Make and Model > Mack > AN - Anthem
Make and Model > Mack > GU/GR - Granite
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Related links and attachments
KC-2165 2581-03-02-01
KC-2165 2589-03-02-42
KC-2165 2589-08-03-05 IMG 1
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KC-2165 2589-08-03-05 IMG 2
KC-2165 2589-08-03-05 IMG 3
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