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P2271






P2271-O2 SENSOR 1/2 OUT OF RANGE LOW

Special Tools:









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

The engine after treatment 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 monitor checks the O2 Sensor 1/1 at zero fueling condition, when the oxygen concentration in the exhaust should be close to air. The PCM will illuminate the MIL lamp if it detects that the actual O2 measurement does not match the expected value in two drive cycles. The PCM will turn off the MIL lamp after the monitor runs and passes in four consecutive drive cycles.

- When Monitored:
This monitor runs when the engine is running at zero fueling event (decel condition for 10 seconds, with foot off of accelerator pedal).

- Set Condition:
The Powertrain Control Module (PCM) will set the fault if it detects that the O2 Sensor 1/2 measurement is too low at zero fueling event.





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

NOTE: This fault can potentially be set by an aftermarket Air Filter Box and/or filter. Non factory filter assemblies are not calibrated to the factory PCM thresholds or settings. If the vehicle has a modified filter assembly and this fault is set, notify the customer that the vehicle needs to be returned back to the stock assembly in order to properly repair the vehicle.

NOTE: Before replacing O2 Sensor or O2 Sensor Module, check after treatment wiring harness for spread terminals. For wiring harness checking procedure, DO NOT back probe, use Electric Terminal Tool Kit (8197A).

1. ACTIVE DTC

NOTE: If there are any cylinder misfire, Crank Sensor, MAF Sensor, Boost Pressure Sensor, Differential Pressure Sensor, or Fuel Injector DTCs stored with this fault, perform the diagnostics for those DTCs before proceeding with this test.

1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Start the engine and drive the vehicle at 50 MPH. Perform a zero fueling event (decel condition for 10 seconds, with foot off of accelerator pedal). Repeat 3-5 times.
6. With the scan tool, read DTCs.

Did the DTC return?

Yes

- Go To 2

No

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

2. CHECK THE (K733) O2 SENSOR 1/2 PUMP CELL CURRENT TRIM CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/2 harness connector.
3. Disconnect the Smart O2 Sensor Module harness connector.
4. Measure the resistance between ground and the (K103) O2 Sensor 1/2 Pump Cell Current Trim circuit at the O2 Sensor 1/2 harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 3

No

- Repair the (K733) O2 Sensor 1/2 Pump Cell Current Trim circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE FUEL DELIVERY SYSTEM
1. Reconnect the O2 Sensor 1/2 harness connector.
2. Reconnect the Smart O2 Sensor Module harness connector.
3. Perform the CHECKING THE FUEL DELIVERY SYSTEM diagnostic procedure. Checking The Fuel Delivery System.

Were any fuel system problems found?

Yes

- Perform the appropriate repairs to the fuel system.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE INTAKE AIR SYSTEM
1. Perform the INTAKE AIR SYSTEM PRESSURE TEST diagnostic procedure. Intake Air System Pressure Test

Were any Intake Air System problems found?

Yes

- Perform the appropriate repairs to the Intake Air System.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 5

5. CHECK THE EXHAUST SYSTEM FOR LEAKS
1. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS diagnostic procedure. Checking The Exhaust System For Leaks

Were any Exhaust System leaks found?

Yes

- Perform the appropriate repairs to the Exhaust System.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 6

6. CHECK FOR AN EGR SYSTEM LEAK
1. Look for visible signs (soot streaks) of an external EGR leak. Check the EGR Valve and EGR Cooler for leaks.

Were any EGR system leaks found?

Yes

- Perform the appropriate repairs to the EGR system.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 7

7. CHECK THE O2 SENSOR

NOTE: Excessive soot build up can be caused by over fueling. If excessive soot build up is present, the fuel system operation should be checked and both of the O2 sensors should be cleaned.

1. Remove the O2 Sensors.
2. Clean the soot from the O2 Sensors.
3. Reinstall the O2 Sensors.
4. Turn the ignition on.
5. With the scan tool, erase DTCs.
6. Turn the ignition off for 75 seconds.
7. Start the engine and drive the vehicle at 50 MPH. Perform a zero fueling event (decel condition for 10 seconds, with foot off of accelerator pedal). Repeat 3-5 times.
8. With the scan tool, read DTCs.

Did the DTC return?

Yes

- Go To 8

No

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

8. O2 SENSOR MODULE
1. Turn the ignition off.
2. Remove the O2 Sensor 1/1 and O2 Sensor 1/2.
3. Install the O2 Sensor 1/1 in the O2 Sensor 1/2 position.
4. Install the O2 Sensor 1/2 in the O2 Sensor 1/1 position.
5. Turn the ignition on.
6. With the scan tool, erase DTCs.
7. Turn the ignition off for 75 seconds.
8. Start the engine and drive the vehicle at 50 MPH. Perform a zero fueling event (decel condition for 10 seconds, with foot off of accelerator pedal). Repeat 3-5 times.
9. With the scan tool, read DTCs.

Did the DTC change to P2196?

Yes

- Reinstall the O2 Sensor 1/1 back to its original position and replace the O2 Sensor 1/2.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the O2 Sensor Module. Return the O2 Sensors back to their original positions.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

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