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Home >> Chrysler >> 2011 >> 300 C, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1574 (6.7L Diesel - DTCS P20B7 To P24A0 - 2500 Hd) >> DTC Troubleshooting >> P20B9-REDUCTANT Heater "A" Control Circuit/Open >> Diagnostic Test

Diagnostic Test

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.
  1. ACTIVE DTC 
    1. Turn the ignition on.
    2. With the scan tool, actuate the line heater.
    3. With the scan tool, view DTCs.

      Is the DTC active?

      Yes 

      • Go To  2

      No 

  2. CHECK THE DEF PRESSURE LINE HEATER SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the DEF Pressure Line Heater harness connector.
    3. Disconnect the DEF Dosing Control Unit C2 harness connector.
    4. Measure the resistance of the DEF Pressure Line Heater Supply circuit between the DEF Pressure Line Heater harness connector and the DEF Dosing Control Unit C2 harness connector.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Go To  3

      No 

      • Repair the DEF Pressure Line Heater Supply circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  3. CHECK THE DEF PRESSURE LINE HEATER RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance of the DEF Pressure Line Heater Return circuit between the DEF Pressure Line Heater harness connector and the DEF Dosing Control Unit C2 harness connector.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Go To  4

      No 

      • Repair the DEF Pressure Line Heater Return circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  4. CHECK THE DEF PRESSURE LINE HEATER 
    1. Measure the resistance across the terminals of the DEF Pressure Line Heater.

      Does the resistance measure between 4.0 Ohms and 10.0 Ohms?

      Yes 

      • Replace the DEF Dosing Control Unit in accordance with the service information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Replace the DEF Pressure Line in accordance with the service information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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