DTC P0140 HO2S Circuit Insufficient Activity Sensor 2. Oldsmobile Intrigue 1999

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 1999 🢒 Intrigue 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P0140 HO2S Circuit Insufficient Activity Sensor 2

Engine Controls Components
Heated Oxygen Sensor (HO2S) #1 and #2
OBD II Symbol Description Notice

Circuit Description

The powertrain control module (PCM) supplies a bias voltage of about 450 mV between the HO2S signal and low circuits. When measured with a 10 megohm digital voltmeter, this may display as low as 320 mV. The oxygen sensor varies the voltage within a range of about 1000 mV when the exhaust is rich, through about 10 mV when the exhaust is lean. The PCM constantly monitors the HO2S signal during closed loop operation and compensates for a rich or lean condition by decreasing or increasing the injector pulse width as necessary. If the HO2S 2 voltage remains at or near the 450 mV bias for an extended period of time, DTC P0140 is set, indicating an open sensor signal or sensor low circuit.

Conditions for Running the DTC

None of the following DTCs are present:

-	Throttle position (TP) sensor DTCs

-	Evaporative emissions (EVAP) DTCs

-	Intake air temperature (IAT) sensor DTCs

-	Manifold absolute pressure (MAP) sensor DTCs

-	Exhaust gas recirculation (EGR) pintle position DTCs

-	Engine coolant temperature (ECT) sensor DTCs

-	Crankshaft position (CKP) sensor DTCs

-	Mass air flow (MAF) sensor DTCs

-	Misfire DTCs

-	Fuel trim DTCs

-	Fuel injector circuit DTCs

The engine run time is more than 240 seconds.

Conditions for Setting the DTC

The HO2S 1 signal voltage remains between 425 mV and 475 mV for up to 90 seconds.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has run and failed.

•	The PCM stores conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

•	The PCM turns the MIL off during the third consecutive trip in which the diagnostic has run and passed.

•	The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

Inspect or test for the following conditions:

•

Any corroded exhaust flange bolts. Use a digital multimeter in order to verify that continuity exists between the engine block and the heated oxygen sensor shell. If the resistance is excessively high, replace the corroded exhaust flange attaching hardware as necessary. Refer to Exhaust System Inspection .

•	Inspect for faulty connection or a damaged harness. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connections , and damage to the harness.

•

Test for a malfunctioning HO2S heater or heater circuit. With the ignition on and the engine not running, the HO2S voltage displayed on a scan tool should gradually drop to below 250 mV or rise to above 600 mV. If the voltage does not rise or drop, disconnect the HO2S and connect a test lamp between the HO2S ignition feed and heater ground circuits. If the test lamp does not illuminate, repair the open ignition feed or sensor ground circuit as necessary. If the test lamp illuminates and the HO2S signal and low circuits are OK, replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement .

•	Test for an intermittent. With the ignition on, monitor the HO2S signal voltage while moving the wiring harness and related connectors. If the malfunction is induced, the HO2S signal voltage changes. This may help isolate the location of the malfunction.

Test Description

The number(s) below refer to the step number(s) on the Diagnostic Table:

If the DTC P0140 test passes while the Fail Records conditions are being duplicated, an intermittent condition is indicated.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

This vehicle is equipped with a powertrain control module (PCM) which utilizes an electrically erasable programmable read-only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

DTC P0140 - HO2S Circuit Insufficient Activity Sensor 2

Step	Action	Value(s)	Yes	No
1	Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	. With the engine at operating temperature, operate the engine above 1200 RPM for 2 minutes while using a scan tool in order to monitor the HO2S 2 voltage. Is the HO2S 2 voltage varying outside the specified range?	425-475 mV	Go to Step 3	Go to Step 4
3	Turn on the ignition switch. Review and record the scan tool Fail Records data and note the parameters. Operate the vehicle within the Fail Records conditions as noted. Use the scan tool in order to monitor the Specific DTC info for DTC P0140 until the DTC P0140 test runs. Does the scan tool indicate DTC Failed This Ign?	--	Go to Step 4	Go to Diagnostic Aids
4	Turn on the ignition switch. Disconnect the HO2S 2 and jumper the HO2S signal and low circuits (PCM side) to ground. Use the scan tool in order to monitor the HO2S 2 voltage. Is the voltage less than the specified value?	150 mV	Go to Step 8	Go to Step 5
5	Remove the jumper wire from the HO2S signal circuit. Leave the HO2S low circuit jumpered to ground. Use a digital multimeter in order to measure the voltage between the HO2S 2 signal circuit (PCM side) and the HO2S 2 heater ground circuit. Does HO2S 2 signal voltage measure near the specified value?	400 mV	Go to Step 6	Go to Step 7
6	Turn off the ignition switch. Disconnect the PCM. Test the continuity of the HO2S 2 low circuit. If the HO2S 2 low circuit measures over 5 ohms, repair an open or a faulty connection as necessary. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 13	Go to Step 9
7	Turn off the ignition switch Disconnect the PCM. Test the continuity of the HO2S 2 signal circuit and the HO2S 2 low circuit between the PCM harness connector and the HO2S 2 harness connector. If the HO2S 2 signal circuit or the HO2S 2 low circuit measures over 5 ohms, repair an open or faulty connection as necessary. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 13	Go to Step 10
8	Test for a faulty HO2S 2 signal or low circuit terminal connection at the HO2S 2 harness connector. If a problem is found, replace the terminal(s) as necessary. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 13	Go to Step 11
9	Test for a faulty HO2S 2 low circuit terminal connection at the PCM. If a problem is found, replace the terminal as necessary. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 13	Go to Step 12
10	Test for a faulty HO2S 2 signal circuit or HO2S low circuit terminal connection at the PCM. If a problem is found, replace the terminal(s) as necessary. Refer to Connector Repairs in Wiring Systems. Was a problem found?	--	Go to Step 13	Go to Step 12
11	Replace the HO2S 2. Refer to Heated Oxygen Sensor Replacement . Did you complete the repair?	--	Go to Step 13	--
12	Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the repair?	--	Go to Step 13	--
13	Turn off the ignition switch. Review and record the scan tool Fail Records data. Clear any DTCs. Operate the vehicle within the Fail Records conditions as noted. Use the scan tool in order to monitor the Specific DTC info for DTC P0140 until the DTC P0140 test runs. Does the scan tool indicate the DTC Failed This Ign?	--	Go to Step 2	System OK