P202A

P202A-(DIESEL EXHAUST FLUID) REDUCTANT TANK HEATER CONTROL CIRCUIT OPEN




For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation

The Diesel Exhaust Fluid (DEF) Tank has an internal heating coil to help eliminate freezing of Diesel Exhaust Fluid. The DEF Dosing Control Unit monitors the temperature of the Diesel Exhaust Fluid inside the tank. When it is determined that the Diesel Exhaust Fluid needs to be heated, the DEF Dosing Control Unit opens the DEF Engine Coolant Valve which is located nest to the DEF Tank, and allows warm engine coolant to circulate through the heating coil inside the tank to warm the Diesel Exhaust Fluid in the tank. The DEF Dosing Control Unit will illuminate the MIL lamp via the PCM immediately after this diagnostic runs and fails. The DEF Dosing Control Unit will turn off the MIL lamp via the PCM immediately after the diagnostic runs and passes for three consecutive key cycles.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
The DEF Dosing Control Unit detects that the DEF Engine Coolant Control Valve circuit is open.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Turn the ignition on for one minute, engine not running.
2. With the scan tool check for active DTCs.

Is the DTC active?

Yes

- Go To 3

No

- Perform the INTERMITTENT CONDITION - 6.7L diagnostic procedure. . Intermittent Condition Test

2. CHECK THE DIESEL EXHAUST FLUID ENGINE COOLANT CONTROL VALVE
1. Turn ignition off.
2. Disconnect the DEF Engine Coolant Control Valve harness connector.
3. Connect a jumper between the (K473) DEF Engine Coolant Control Valve Signal circuit and the (K474) DEF Engine Coolant Control Valve Return circuit at the DEF Engine Coolant Control Valve harness connector.

NOTE: Be careful not to spread the terminals in the connector.

4. Turn the ignition on.
5. With a scan tool, View DTCs.

Does the scan tool display DTC P202B as active and P202A as stored with the jumper in place?

Yes

- Replace the DEF Engine Coolant Control Valve. Diesel Exhaust Fluid Engine Coolant Control Valve - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. CHECK THE (K473) DIESEL EXHAUST FLUID ENGINE COOLANT CONTROL VALVE SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE




1. Turn ignition off.
2. Disconnect the DEF Dosing Control Unit C1 harness connector.
3. Measure the resistance of the (K473) DEF Engine Coolant Control Valve Signal circuit between the DEF Dosing Control Unit C1 harness connector and the DEF Engine Coolant Control Valve harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the (K473) DEF Engine Coolant Control Valve Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. CHECK THE (K474) DIESEL EXHAUST FLUID ENGINE COOLANT CONTROL VALVE RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE




1. Measure the resistance of the (K474) DEF Engine Coolant Control Valve Return circuit between the DEF Dosing Control Unit C1 harness connector and the DEF Engine Coolant Control Valve harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Replace the DEF Dosing Control Unit. Diesel Exhaust Fluid Dosing Control Unit - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Repair the (K474) DEF Engine Coolant Control Valve Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.