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Home >> Chrysler >> 2011 >> 300 C, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1574 (6.7L Diesel - DTCS P20B7 To P24A0 - 2500 Hd) >> DTC Troubleshooting >> P21C4-(Diesel Exhaust Fluid) REDUCTANT Line Heater Relay Control Circuit High >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes
SCR RELAY 1 HEATER SUPPLY CIRCUIT SHORTED TO VOLTAGE
POWER DISTRIBUTION CENTER
DEF DOSING CONTROL UNIT

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to  PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE  . 

NOTE:

The DEF Heater monitor runs only when the DEF Heater Relay is on. If the ambient temperature is too warm for the DEF Heaters to be turned on, the DTC will remain active and will not be able to be erased after repair is completed. Using the scan tool, navigate to Actuator Tests and actuate the Heater Relay test for the appropriate Heater to run the diagnostic and determine if the repair has been completed. If the repair is complete, the fault will move to stored and be able to be cleared with the scan tool.