DTC P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2

Circuit Description

The PCM supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.

The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.

The PCM monitors the HO2S voltage and detects if the voltage goes out of the bias range. If the PCM does not detect the voltage went out of the bias range, a DTC sets.

Conditions for Running the DTC

• DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0335, P0336, P0351-P0358, P1258 not set.
• The engine run time is greater than 70 seconds.
• The fuel system is operating in Closed Loop.
• The AIR, EGR, and the Catalyst diagnostics are not active.
• The engine coolant temperature is greater than 48°C (118°F).

Conditions for Setting the DTC

The HO2S signal voltage is steady between 409 mV and 489 mV for 2.5 minutes.

Action Taken When the DTC Sets

• The PCM illuminates the malfunction indicator lamp when the diagnostic runs and fails.
• The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or the Failure Records.
• The engine operates in Open Loop Fueling.

Conditions for Clearing the MIL/DTC

• The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

Important

• Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.
• For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents any damage to the harness connector terminals.

• An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems.
• For an intermittent condition, refer to Symptoms .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2. The engine must be at the normal operating temperature before performing this test. For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness connector terminals.

3. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicated the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. Refer to Symptoms for further diagnosis.

4. Lower the exhaust system in order to gain sufficient access to the HO2S and/or it's connector. Refer to Catalytic Converter Replacement in Engine Exhaust. If the scan tool indicates the HO2S voltage goes below 200 mV, indicates the HO2S circuits and PCM are OK.

5. This step tests whether the signal circuit from the PCM is OK.

6. Disconnecting the PCM allows using the DMM J 39200 in order to test continuity of the circuits. This aids in locating an open or shorted circuit.

7. Disconnecting the PCM allows using the DMM J 39200 in order to test continuity of the circuits. This aids in locating an open or shorted circuit.

Step	Action	Value(s)	Yes	No
1	Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to A Powertrain On Board Diagnostic (OBD) System Check
2	Important Before proceeding with this DTC, inspect the HO2S for being secure. A sensor that is loose could cause this DTC to set. Install the scan tool. Idle the engine until the normal operating temperature is reached. Operate the engine above 1,200 RPM for two minutes. Monitor the HO2S voltage display on the Engine 1 Data List using the scan tool. Does the scan tool indicate the HO2S voltage varying outside the specified range?	409-489 mV	Go to Step 3	Go to Step 4
3	Turn ON the ignition leaving the engine OFF. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters. Turn OFF the ignition for 15 seconds. Start the engine. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, and then enter the DTC number using the scan tool. Does the scan tool indicate that this diagnostic failed this ignition?	--	Go to Step 4	Go to Diagnostic Aids
4	Turn ON the ignition leaving the engine OFF. Disconnect the HO2S. Jumper the HO2S high and low (PCM side) signal circuits to ground. Monitor the HO2S voltage using the scan tool. Is the HO2S voltage below the specified value?	200 mV	Go to Step 8	Go to Step 5
5	Remove the jumper wire. Measure the voltage between the HO2S high signal circuit (PCM side) and the HO2S heater ground circuit using the DMM J 39200 . Does the HO2S voltage measure above the specified value?	375 mV	Go to Step 6	Go to Step 7
6	Turn OFF the ignition. Disconnect the PCM connector C2 located on the same side as the manufacturer's logo. Refer to PCM Replacement/Programming . Test the continuity of the HO2S low circuit. Refer to Testing for Continuity in Wiring Systems. Repair the open or the poor connection if the HO2S low circuit measures over the specified value. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	2ohms	Go to Step 13	Go to Step 9
7	Turn OFF the ignition. Disconnect the PCM connector C2 located on the same side as the manufacturer's logo. Refer to PCM Replacement/Programming . Test the continuity of the HO2S signal circuit. Refer to Testing for Continuity in Wiring Systems. Repair the open or the poor connection if the HO2S signal circuit measures over the specified value. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	2ohms	Go to Step 13	Go to Step 10
8	Inspect for a poor connection at the HO2S signal or low circuit. . Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. If you find a poor connection, repair/replace the terminal(s) as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 13	Go to Step 11
9	Test for a poor connection at the HO2S low circuit terminal at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. If you find a poor connection, repair/replace the terminal(s) as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 13	Go to Step 12
10	Test for a poor connection at the HO2S signal circuit terminal at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. If you find a poor connection, repair/replace the terminal(s) as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 13	Go to Step 12
11	Replace the HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement - Bank 1 . Is the action complete?	--	Go to Step 13	--
12	Important: Program the replacement PCM. Refer to PCM Replacement/Programming . Replace the PCM. Is the action complete?	--	Go to Step 13	--
13	Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool. Idle the engine at the normal operating temperature. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable. Does the scan tool indicate that this test ran and passed?	--	Go to Step 14	Go to Step 2
14	Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed?	--	Go to the applicable DTC table	System OK