CYLINDER AS 1412916 - Caterpillar

Probable Causes
Codes
Backflow line
DEF pump
Backflow valveRecommended Actions
Illustration 1 g06300650
The DEF pumps are on the front side of the Pump Electronic Tank Unit (PETU).
(1) Coolant diverter valve for Aftertreatment #2 DEF pump #2 system (red)
(2) Aftertreatment #2 DEF pump #2 header (red)
(3) Aftertreatment #2 DEF pump #1 header (yellow)
(4) Coolant diverter valve for Aftertreatment #2 DEF pump #1 system (yellow)
(5) DEF backflow valve for Aftertreatment #2 DEF pump #2 system (red)
(6) DEF backflow valve for Aftertreatment #2 DEF pump #1 system (yellow)
(7) Aftertreatment #2 DEF pump #2 (red)
(8) Aftertreatment #2 DEF pump #1 (yellow)
(9) Aftertreatment #1 DEF pump #2 (green)
(10) Aftertreatment #1 DEF pump #1 (blue)
(11) DEF backflow valve for Aftertreatment #1 DEF pump #2 system (green)
(12) DEF backflow valve for Aftertreatment #1 DEF pump #1 system (blue)
(13) Coolant diverter valve for Aftertreatment #1 DEF pump #2 system (green)
(14) Aftertreatment #1 DEF pump #2 header (green)
(15) Aftertreatment #1 DEF pump #1 header (blue)
(16) Coolant diverter valve for Aftertreatment #1 DEF pump #1 system (blue)
Table 2
Troubleshooting Test Steps Values Results
1. Check the Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Look for active codes that are associated with the system for the event code.
Codes
Result: An associated code is active.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: A code is active or logged.
Proceed to Test Step 2.
2. Check the Backflow Lines for a Restriction
A. Turn the keyswitch to the OFF position. Allow 2 minutes to elapse before proceeding.
B. Remove the appropriate backflow line between the backflow valve and the Diesel Exhaust Fluid (DEF) tank header.
C. Inspect the backflow lines for obstructions. Flush line with water/low pressure air if necessary.
Possible obstructions are ice, DEF deposits, or debris.
Restriction
Result: An obstruction was found in the backflow line.
Repair: Flush the line or replace the line.
Proceed to Test Step 5.
Result: An obstruction was not found in the backflow line.
Proceed to Test Step 3.
Illustration 2 g06026979
Table 3
3. Check for a Restriction in the DEF Pump
A. Reinstall the backflow line onto the DEF pump. Place the end of the line that would normally be installed onto the backflow valve into a beaker to collect the