P241A

P241A-O2 SENSOR 1/1 AND 1/2 OXYGEN CONCENTRATION MISMATCH

Special Tools:









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

The engine aftertreatment system monitors the oxygen content in the exhaust. The Powertrain Control Module (PCM) monitors the exhaust gases for oxygen content and varies the fuel injector on time to control the intake air fuel mixture. This diagnostic monitors the delta reading between the upstream and downstream O2 Sensors. The PCM will illuminate the MIL lamp when the diagnostic runs and fails in two drive cycles. The PCM will turn off the MIL lamp diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
This diagnostic runs when the engine is running.

- Set Condition:
The Powertrain Control Module (PCM) will set the fault if the delta reading between the O2 Sensors is too large.





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

NOTE: Before replacing O2 Sensor or O2 Sensor Module, check aftertreatment wiring harness for spread terminals. For wiring harness checking procedure, DO NOT back probe, use Electric Terminal Tool Kit.

1. OTHER DTC
1. Turn the ignition on.
2. With the scan tool, read DTCs.

Are there any other O2 Sensor circuit low or high related DTCs present?

Yes

- Repair other O2 Sensor related DTCs first.

No

- Go To 2

2. CHECK THE NOX ABSORBER CATALYST FOR DAMAGE OR LEAKS
1. Turn the ignition off.
2. Separate the exhaust system and inspect the NOx Absorber Catalyst for damage or leaks.

Were any problems found?

Yes

- Replace the NOx Absorber Catalyst.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. OXYGEN SENSOR SOOTED
1. Remove the O2 Sensors.
2. Carefully clean the soot from the O2 Sensor.

NOTE: Do not tap or bang the sensor to remove loose debris. This will damage the sensor.

3. Reinstall the O2 Sensors.
4. With the scan tool, erase DTCs.
5. Turn the ignition off for 75 seconds.
6. Start the engine and drive the vehicle, varying between 0 and 50 mph.
7. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Replace both O2 Sensors.
- Go To 4

No

- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. OXYGEN SENSOR MODULE
1. With the scan tool, erase DTCs.
2. Turn the ignition off for 75 seconds.
3. Start the engine and drive the vehicle, varying between 0 and 50 mph.
4. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Replace the O2 Sensor Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.