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P2246






P2246-O2 SENSOR 1/1 REFERENCE VOLTAGE CIRCUIT HIGH

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





Theory of Operation

The wide-band O2 Sensor operates differently than traditional O2 Sensors. The wide-band O2 Sensor tip consists of two cells that provide different functions, a measurement chamber and a detection chamber with pumping capabilities. The oxygen pumping function is the ability to pump oxygen into or out of the measurement chamber depending on the level of oxygen in the measurement chamber. This function provides the wide-band sensing capabilities and is critical for proper oxygen measurement. The O2 Sensor Reference circuit provides a common bias supply to both the O2 Sensor Signal and the O2 Sensor Pump Cell Current circuits.

During normal operation, the O2 Sensor Reference voltage and O2 Sensor Signal voltage will be a fixed voltage value. The O2 Sensor Current Pump voltage will switch from between 0.45 volts above and below the fixed O2 Sensor Return voltage, allowing current to flow in either direction through the pump. This correlates with the pumping of oxygen into and out of the measurement chamber. On a properly operating vehicle, this happens very quickly and the voltage reading should maintain a steady 0.45 volts when taking a voltage measurement between the O2 Sensor Signal circuit and the O2 Sensor Reference circuit of the O2 Sensor with the engine running and the O2 Sensor operating in closed loop.

When the exhaust stream has a lean air/fuel ratio (high oxygen content) the pumping element voltage will move toward +0.45 volts pumping oxygen out of the measurement chamber. When the exhaust stream has a rich air/fuel ratio (relatively low oxygen content) the pumping element voltage will move toward -0.45 volts pumping oxygen into the measurement chamber.

- When Monitored:
With the ignition on, the O2 Sensor 1/1 at operating temperature, pump cell active, and P0131 and P0132 are not active.

- Set Condition:
The Powertrain Control Module (PCM) detects a high voltage reading on the (K902) O2 Sensor 1/1 Return circuit. After the first fault is detected the sensor is shutdown and re-initialized which takes 9 seconds after which the test is repeated. A fault is set after the monitor runs and fails for 7 counts.





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

Diagnostic Test

1. CHECK THE O2 SENSOR VOLTAGE READINGS
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/1 harness connector.
3. Connect the Wide-band O2 Sensor Diagnostic Adaptor 10367 in-line of the O2 Sensor 1/1 harness connector.
4. Start the engine and bring the engine speed up to 2500 RPM.
5. With the engine steady at 2500 RPM, measure the voltage:
- at the (K41) O2 Sensor Signal circuit at the appropriate terminal of the Wide-band O2 Sensor Diagnostic Adaptor 10367 tool.
- at the (K902) O2 Sensor Return circuit at the appropriate terminal of the Wide-band O2 Sensor Diagnostic Adaptor 10367 tool.
- at the (K89) O2 Sensor Pump Current circuit at the appropriate terminal of the Wide-band O2 Sensor Diagnostic Adaptor 10367 tool.
- between the (K89) O2 Sensor Pump Current circuit and the (K902) O2 Sensor Return circuit at the appropriate terminals of the Wide-band O2 Sensor Diagnostic Adaptor 10367 tool.

NOTE: If the Powertrain Control Module detects an active open or short on any of the O2 Sensor 1/1 circuits, it will power down all of the O2 Sensor circuits to protect the O2 Sensor and PCM internal ASIC from being damaged.

6. If the O2 Sensor is powered up by the PCM and operating normal, the voltage readings should be as follows;
- The voltage at the (K41) O2 Sensor Signal circuit should be approximately 4.3 volts.
- The voltage at the (K902) O2 Sensor Return circuit should be approximately 3.85 volts.
- The voltage at the (K89) O2 Sensor Pump Current circuit should be switching between approximately 3.4 volts and 4.3 volts.
- The voltage between the (K89) O2 Sensor Pump Current circuit and the (K902) O2 Sensor Return circuit should switch between +0.45 volts and -0.45 volts.

NOTE: The voltage readings may vary up or down slightly depending on the age of the O2 Sensor and operating conditions of the engine. However, if the engine and O2 Sensor are operating normal the voltage reading between the (K89) O2 Sensor Pump Current circuit and the (K902) O2 Sensor Return circuit should switch between +0.45 volts and -0.45 volts with very little or no change.

Do the circuit voltages read as described?

Yes

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

No

- Go To 2

2. CHECK THE (F343) FUSED ASD RELAY OUTPUT VOLTAGE
1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/1 harness connector.
3. Remove the Wide-band O2 Sensor Diagnostic Adaptor 10367 tool. Leave the O2 Sensor 1/1 harness connector disconnected.
4. Turn the ignition on.
5. Measure the voltage on the (F343) Fused ASD Relay Output circuit at the O2 Sensor 1/1 harness connector.

Does the voltage read battery voltage?

Yes

- Go To 3

No

- Repair the (F343) Fused ASD Relay Output circuit for an open or short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. CHECK THE O2 SENSOR CIRCUITS FOR A SHORT TO VOLTAGE
1. Measure for voltage at the:
- (K41) O2 Sensor 1/1 Signal circuit at the O2 Sensor 1/1 harness connector.

- (K902) O2 Sensor 1/1 Return circuit at the O2 Sensor 1/1 harness connector.

- (K89) O2 Sensor 1/1 Current Pump Control circuit at the O2 Sensor 1/1 harness connector.

NOTE: With the O2 Sensor disconnected, the PCM will power down the O2 Sensor and there should be no voltage on the circuits.

Do any of the circuits measure above 0.5 volts?

Yes

- Repair the circuit that measured above 0.5 volts for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE O2 SENSOR CIRCUITS FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between ground and the:
- (K41) O2 Sensor 1/1 Signal circuit at the O2 Sensor 1/1 harness connector.

- (K902) O2 Sensor 1/1 Return circuit at the O2 Sensor 1/1 harness connector.

- (K89) O2 Sensor 1/1 Current Pump Control circuit at the O2 Sensor 1/1 harness connector.

- (K79) O2 Sensor 1/1 Heater Control circuit at the O2 Sensor 1/1 harness connector.

Is the resistance above 10k Ohms between each of the above circuits and ground?

Yes

- Go To 5

No

- Repair the circuit that measured above below 10k Ohms for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. CHECK THE O2 SENSOR CIRCUITS FOR AN OPEN OR HIGH RESISTANCE
1. Measure the resistance of the:
- (K41) O2 Sensor 1/1 Signal circuit between the O2 Sensor 1/1 harness connector and the PCM C1 harness connector.

- (K902) O2 Sensor 1/1 Return circuit between the O2 Sensor 1/1 harness connector and the PCM C1 harness connector.

- (K89) O2 Sensor 1/1 Current Pump Control circuit between the O2 Sensor 1/1 harness connector and the PCM C1 harness connector.

- (K79) O2 Sensor 1/1 Heater Control circuit between the O2 Sensor 1/1 harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms for each of the above circuits?

Yes

- Go To 6

No

- Repair the circuit that measured above 5.0 Ohms for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. O2 SENSOR
1. Turn the ignition off.
2. Reconnect the PCM C1 harness connector.
3. Replace the O2 Sensor and reconnect the harness connector.
4. Turn the ignition on.
5. With the scan tool, erase DTCs.
6. Start the engine and allow it to idle long enough for the O2 Sensor to enter closed loop operation.
7. With the scan tool, view DTCs.

Did the DTC return?

Yes

- Go To 7

No

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

7. POWERTRAIN CONTROL MODULE (PCM)

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the O2 Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module harness connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

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