DTC P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2. Cadillac Seville 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Seville 🢒 DTC 🢒 DTC P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2

Engine Controls Component Views
HO2S
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The HO2S is a sensor used to detect oxygen-content in the exhaust. The PCM supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal.

The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, the PCM adjusts the injector pulse width. If HO2S bank 1 sensor 2 remains at, or near the bias voltage for a calibrated period of time, DTC P0140 will set.

Conditions for Running the DTC

•	TP sensor, MAF sensor, MAP sensor, IAT sensor, ECT sensor, HO2S heater, EVAP system, AIR system (if equipped), fuel injector, EGR system DTCs are not set.

•	Engine run time is more than 200 seconds (3 minutes).

•	TP angle is between 3 and 25 percent.

•	A change in TP angle more than 5 percent occurs at least 7 times.

•	System voltage is between 9 and 18 volts.

•	Closed loop fuel control is enabled.

•	Air fuel ratio is between 14.4 and 14.9

•	Catalyst test inactive.

•	AIR test inactive.

•	The conditions above are met for 5 seconds.

Conditions for Setting the DTC

HO2S bank 1 sensor 2 signal voltage remain within 400 and 500 mV for approximately 190 seconds (approximately 3 minutes).

Action Taken When the DTC Sets

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

•	The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.

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

•	The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

Notice: Do not solder heated oxygen sensor wires. Soldering the wires will result in the loss of the air reference to the sensor. Refer to Engine Electrical for proper wire and connection repair techniques.

For intermittent conditions, refer to Symptoms .

Step

Action

Values

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn ON the ignition, with the engine OFF.
With a scan tool, clear the DTCs.
With a scan tool, monitor the DTC information for 30 seconds.

Does DTC P0036 set?

Go to DTC P0036 HO2S Heater Control Circuit Bank 1 Sensor 2

Go to Step 3

With a scan tool, command the HO2S Heater Driver 4 ON.
With a scan tool, monitor the HO2S bank 1 sensor 2 voltage parameter.

Does the scan tool indicate the HO2S voltage varying outside the specified range?

400-500 mV

Go to Step 4

Go to Step 5

Review and record scan tool Freeze Frame and/or Failure Records data.
Operate the vehicle within the Freeze Frame and/or Failure Records conditions.
With a scan tool, monitor the DTC Information.

Does the scan tool indicate the DTC failed this ignition?

Go to Step 5

Go to Diagnostic Aids

Turn OFF the ignition.
Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
Disconnect the HO2S bank 1 sensor 2 harness connector.
Turn ON the ignition, with the engine OFF.
Connect a Jumper wire between the HO2S bank 1 sensor 2 signal high and low circuits -- PCM side.
With a scan tool, observe the HO2S bank 1 sensor 2 voltage display on the scan tool.

Does the scan tool indicate the HO2S bank 1 sensor 2 voltage is below the specified value?

75 mV

Go to Step 9

Go to Step 6

Connect a Jumper wire between the HO2S bank 1 sensor 2 high signal circuit and a good ground.

Does the scan tool indicate the HO2S bank 1 sensor 2 voltage is below the specified value?

150 mV

Go to Step 8

Go to Step 7

Turn OFF the ignition.
Disconnect the PCM connector C1. Refer to Powertrain Control Module Replacement/Programming .
Test the bank 1 sensor 2 high signal circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

Turn OFF the ignition.
Disconnect the PCM connector C1. Refer to Powertrain Control Module Replacement/Programming .
Test the bank 1 sensor 2 low signal circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

Inspect for poor connections at the harness connector of the HO2S bank 1 sensor 2. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

Important: If the sensor appears contaminated, correct the source of the oxygen sensor contamination before replacing the sensor in order to prevent future contamination. Typical contamination sources include the following:

•	Fuel contamination, refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Use of improper RTV sealant

•	Engine oil or engine coolant consumption, refer to Oil Consumption Diagnosis in Engine Mechanical.

Replace the bank 1 sensor 2 heated oxygen sensor. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 .

Did you complete the replacement?

Go to Step 13

Important:: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

Go to Step 13

Observe and record the scan tool Freeze Frame and/or Fail Records Information.
With a scan tool, clear the DTCs.
Operate the vehicle within the parameters listed in the Conditions for Running the DTC.
With a scan tool, monitor the DTC Information.

Does the scan tool display the DTC ran and passed?

System OK

Go to Step 2