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Home >> Chrysler >> 2011 >> 300 C, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 435 (6.7L Diesel - DTCS P1209 To P2281 - 2500 Hd & 3500 Hd) >> Diagnosis And Testing >> P21C4-(Diesel Exhaust Fluid) REDUCTANT Line Heater Relay Control Circuit High >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes 
SCR RELAY 1 CONTROL CIRCUIT SHORTED TO VOLTAGE
SCR RELAY 1
DEF DOSING CONTROL UNIT

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to  STANDARD PROCEDURE  . 

NOTE:

The DEF Heater monitor runs only when the DEF Heater Relay is commanded 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.