74268A 4 Mercruiser PROPELLER, Stainless Steel (21 Pitch)

Table 1
Diagnostic Trouble Codes for DEF Line Heater
J1939 Code Code Description Comments
4354-5 Aftertreatment #1 DEF Line Heater #1 : Current Below Normal This code indicates that there is a fault in the #1 line heater circuit that is probably an open circuit.
4354-6 Aftertreatment #1 DEF Line Heater #1 : Current Above Normal This code indicates that there is a fault in the #1 line heater circuit that is probably a short circuit.
4355-5 Aftertreatment #1 DEF Line Heater #2 : Current Below Normal This code indicates that there is a fault in the #2 line heater circuit that is probably an open circuit.
4355-6 Aftertreatment #1 DEF Line Heater #2 : Current Above Normal This code indicates that there is a fault in the #2 line heater circuit that is probably a short circuit.
4356-5 Aftertreatment #1 DEF Line Heater #3 : Current Below Normal This code indicates that there is a fault in the #3 line heater circuit that is probably an open circuit.
4356-6 Aftertreatment #1 DEF Line Heater #3 : Current Above Normal This code indicates that there is a fault in the #3 line heater circuit that is probably a short circuit.
Follow the troubleshooting procedure to identify the root cause of the fault.
Illustration 1 g06327796
Schematic diagram of the DEF line heater circuit
Note: All connectors may not be shown. Refer to the Electrical Schematic for the application for details of any connectors between the line heater connectors and the ECM connectors.
Table 2
Troubleshooting Test Steps Values Results
1. Check the Battery Voltage
A. Turn