P229E

P229E-AFTERTREATMENT NOx SENSOR CIRCUIT - BANK 1 SENSOR 2





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

Theory of Operation

The aftertreatment system is equipped with two Nox Sensors and modules. The upstream NOx Sensor 1/1 is located before the SCR Catalyst and is permanently connected to a corresponding Nox Sensor Module mounted on the right frame rail. The downstream NOx Sensor 1/2 is located at the outlet of the SCR Catalyst and is permanently connected to a corresponding Nox Sensor Module also mounted on the right frame rail. The NOx Sensors and NOx Sensor Modules are calibrated to each other and must be replaced as an assembly. The two NOx Sensor and Module assemblies are not interchangeable. The NOx Sensor Modules are smart devices and communicate with the Powertrain Control Module (PCM) over the J1939 Data Link. The NOx Sensor Modules perform their own internal diagnostics and report malfunctions back to the PCM. The NOx Sensors are used to monitor the efficiency of the SCR Catalyst and dosing system. The PCM will illuminate the MIL lamp immediately after the monitor runs and fails. The PCM will turn off the MIL Lamp after the monitor runs and passes for three consecutive trips.

- When Monitored:
Continuously with engine running.

- Set Condition:
The NOx Sensor 1/2 detects that the voltage supplied is above or below it's calibrated limits.





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

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, View DTCs.

Is the DTC active?

Yes

- Go To 3

No

- Go To 2

2. CHECK THE NOx 1/2 SENSOR INTERNAL HEATER
1. Start the engine and allow it to idle for at least two minutes.
2. With the scan tool, View DTCs.

Is the DTC active?

Yes

- The NOx Sensor 1/2 internal heater has malfunctioned. Replace the NOx Sensor 1/2. . Bank 1 Sensor 2

No

- Go To 3

3. CHECK THE NOx SENSOR 1/2 POWER AND GROUND CIRCUITS
1. Turn the ignition on, engine not running.
2. Disconnect the NOx Sensor Module 1/2 harness connector.
3. Measure the voltage across the (F505) Fused Ignition Switch Output circuit and the (Z914) Ground circuit at the NOx Sensor Module 1/2 harness connector.

NOTE: Measure the voltage at key on, engine cranking, and at idle.

Does the voltage read within 1.0 Volt of battery voltage?

Yes

- Replace the NOx Sensor 1/2. . Bank 1 Sensor 2
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK FOR VOLTAGE AT THE (F505) FUSED IGNITION SWITCH OUTPUT CIRCUIT
1. Measure voltage between ground and the (F505) Fused Ignition Switch Output circuit of the NOx Sensor Module 1/2 harness connector.

Does the voltage read within 1.0 Volt of battery voltage?

Yes

- Repair the (Z914) Ground circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Repair the (F505) Fused Ignition Switch Output circuit for an open or high resistance. If the fuse is found to be open, check the circuit for a short to the (Z914) Ground circuit or a short to chassis ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.