Solution K58203603
Wednesday, December 4, 2019 9:42:22 PM CET

** SOLUTION **
Title

Diagnostic Trouble Code (DTC) P20EE - SCR NOx Catalyst Efficiency Below
Threshold (Bank 1) - US17+OBD2019 Emissions, Model Year 2020 ONLY

Mack Models
Mack Model

AN - Anthem , CHU - Pinnacle, Axle back , CXU - Pinnacle, Axle front , GR - Granite
, GU - Granite , PI - Pinnacle

Volvo Models
Volvo Model

VN , VNL , VNR , VNX , VAH , VHD

Emission Standard
Emission Standard

US17+OBD19

Engine family
Engine family

11L Engine , 13L Engine , MP7 , MP8

** SOLUTION **
Cause

Trucks built for emissions level US17+OBD19 (Model year 2020) and equipped with a
one-box exhaust aftertreatment system (DPF, DOC and SCR are contained in one unit)
have shown a higher than normal occurrence of fault code P20EE logged in the field.
Affected vehicles have been observed having large urea crystal buildup starting from the
DEF dosing valve. When applicable SCR mufflers are evaluated following removal of
the DEF crystals, the SCR functions as good as a new component.

Solution

Return Visit
If the vehicle has been in for this issue previously an eService case should be started for
further assistance AFTER verifying that the same problem exists.
The eService case MUST INCLUDE:
• The CBR Diagnostic Session number or this Solution number.
• A thorough description of the problem.
• The vehicles previous history and what was done to resolve the issue on previous visits (This
solution MUST have been performed previously if a case is being opened!).
• A complete DTC readout from the time of the vehicle's arrival.

First Visit
1. Verify the chassis emissions level and ensure that the vehicle is within the applicable

range for this solution.
Details can be found in the Product Details box on the Product tab in PTT as seen below:

2. Remove the DEF dosing valve and inspect for crystal buildup.
An example of expected crystal buildup can be seen below:

2.1. If crystal buildup is similar to that shown in the picture above: Continue to Step
3.

2.2 If there are no crystals present, or the crystal accumulation is light with small
crystals: Proceed to and complete solution K65527708.
3. Remove the DPF (Tear Drop) cover and clean the crystal accumulation out of the
pipes.
3.1. With a damp cloth, wipe off the DEF dosing valve and mixing vanes.
4. Once the inside of the muffler is clean, Install new gaskets and V-clamps clamps for the
tear drop cover.
5. Re-install the cover.
6. Remove and discard the insulator (gasket) from the dosing valve. The part is
highlighted in the picture below.

7. Re-install the DEF dosing valve WITHOUT a new insulator. Make sure to use a new
sealing plate and new mounting screws (one time use parts).

8. Clear fault codes.
9. Perform a Sulfur Regeneration. This will complete the cleaning of the SCR.
10. Release the vehicle.

This is a temporary containment for this issue. This solution will be updated when more
information is available.
Internal comments (FO)

This is a containment.
If a truck has P20EE without urea crystals or if a truck returns with crystallization even
after containment please contact Nataraj Bhat/ John Whelan for additional analysis.

Temporary solution

Temporary solution

Solution visibility

Dealer distribution

Function(s)/component(s) affected
Function affected

SCR , DEF Dosing

Function Group
Function Group

254 catalytic converter; exhaust emission control equipment , 2584 Dosage Valve;
Injector

Customer effect
Main customer effect

regeneration , fault code/display

Fluid implicated

Diesel Exhaust Fluid (DEF)

Fault Codes And Error Codes
OBDII Diagnostic Trouble
Codes (P, U, B Format)

P0422-00 , P103C-00 , P20EE-00 , P225C-00

Administration
Author

UT0031H

Dealer ID

UT0031H

Last modified by

RU4469V

Creation date

16-10-2019 19:10

Date of last update

13-11-2019 20:11

Review date

16-12-2019 00:12

Status

Published

NA_Reviewer

UT0031H

UNCONTROLLED COPY. Printed document is for temporary use only and should not be retained.