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Home >> Dodge or Ram Truck >> 2012 >> RAM 3500 Truck 2WD L6-6.7L DSL Turbo High Output >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P2A01

P2A01






P2A01-O2 SENSOR 1/2 CIRCUIT PERFORMANCE

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 diagnostic checks to make sure that the oxygen content matches the expected oxygen content for the engine operating conditions. The PCM will set the fault if it detects that the actual O2 Sensor measurement does not match the expected value. The PCM will illuminate the MIL lamp when the monitor 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 monitor runs when the engine is running, the coolant temperature is above 176°F (80°C) for 20 seconds, the NOx Catalyst outlet temperature is above 266°F (130°C) for 20 seconds, the exhaust system is not in regeneration mode, and the vehicles accelerates and decelerates repeatedly.

- Set Condition:
The PCM will set the fault if it detects that the actual O2 Sensor measurement does not match the expected variation.





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

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: 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: If there are any cylinder misfire, Crank Sensor, MAF 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 warm the coolant to 176°F (80°C). Verify with the scan tool that the vehicle is in normal operating mode and not in Desoot.
6. Drive the vehicle at 30 MPH for 2-3 minutes, increase the speed to 50 MPH for 2-3 minutes and then decrease the speed back to 30 MPH for 2-3 minutes.
7. With the scan tool, read DTCs.

Did the DTC return?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. CHECK THE (K733) O2 SENSOR 1/2 PUMP CELL CURRENT TRIM CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/2 harness connector.
3. Disconnect the O2 Sensor Module harness connector.
4. Measure the resistance of the (K733) O2 Sensor 1/2 Pump Cell Current Trim circuit between the O2 Sensor 1/2 harness connector and the O2 Sensor Module harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 3

No

- Repair the (K733) O2 Sensor 1/2 Pump Cell Current Trim circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE (K734) O2 SENSOR 1/2 POSITIVE CURRENT CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K734) O2 Sensor 1/2 Positive Current Control circuit between the O2 Sensor 1/2 harness connector and the O2 Sensor Module harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the (K734) O2 Sensor 1/2 Positive Current Control circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. CHECK THE (K141) O2 SENSOR 1/2 SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K141) O2 Sensor 1/2 Signal circuit between the O2 Sensor 1/2 harness connector and the O2 Sensor Module harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the (K141) O2 Sensor 1/2 Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. CHECK THE (K904) O2 SENSOR 1/2 RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K904) O2 Sensor 1/2 Return circuit between the O2 Sensor 1/2 harness connector and the O2 Sensor Module harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the (K904) O2 Sensor 1/2 Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. CHECK THE FUEL DELIVERY SYSTEM
1. Reconnect the O2 Sensor 1/1 harness connector.
2. Reconnect the 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 DIESEL AFTERTREATMENT VALIDATION - 6.7L. Component Tests and General Diagnostics

No

- Go To 7

7. 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 DIESEL AFTERTREATMENT VALIDATION - 6.7L. Component Tests and General Diagnostics

No

- Go To 8

8. 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 DIESEL AFTERTREATMENT VALIDATION - 6.7L. Component Tests and General Diagnostics

No

- Go To 9

9. CHECK FOR AN EGR LEAK
1. Look for visible signs (soot streaks) of an external EGR leak.

Were any EGR leaks found?

Yes

- Perform the appropriate repairs to the EGR system.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L. Component Tests and General Diagnostics

No

- Go To 10

10. 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 warm the coolant to 176°F (80°C). Verify with the scan tool that the vehicle is in normal operating mode and not in Desoot.
8. Drive the vehicle at 30 MPH for 2-3 minutes, increase the speed to 50 MPH for 2-3 minutes and then decrease the speed back to 30 MPH for 2-3 minutes.
9. With the scan tool, read DTCs.

Did the DTC return?

Yes

- Go To 11

No

- Repair complete.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L. Component Tests and General Diagnostics.

11. 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 warm the coolant to 176°F (80°C). Verify with the scan tool that the vehicle is in normal operating mode and not in Desoot.
9. Drive the vehicle at 30 MPH for 2-3 minutes, increase the speed to 50 MPH for 2-3 minutes and then decrease the speed back to 30 MPH for 2-3 minutes.
10. With the scan tool, read DTCs.

Did the DTC change to P2A00?

Yes

- Reinstall the O2 Sensor 1/1 back to its original position and replace the O2 Sensor 1/2.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L. Component Tests and General Diagnostics.

No

- Replace the O2 Sensor Module. Return the O2 Sensors back to their original positions.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L. Component Tests and General Diagnostics
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