GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 S10 Pickup - 4WD 🢒 Bulletins 🢒 SMU - Revised DTC P0140

SMU - Revised DTC P0140

Subject:Revised DTC P0140

Models:1998-1999 Chevrolet Malibu
1998-2001 Chevrolet Cavalier
2002 Chevrolet Cavalier (2.4L Only)
1998 Oldsmobile Achieva
1999-2001 Oldsmobile Alero
1998-2001 Pontiac Grand Am
1998-2001 Pontiac Sunfire
2002 Pontiac Sunfire (2.4L Only)
2000-2002 Chevrolet and GMC S/T Pick Up Models (Sonoma, S10)
with 2.2L or 2.4L Engine (VINs 4, 5, T -- RPOs LN2, L43, LD9)


This bulletin is being issued to revise DTC P0140 in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.

The following information has been updated within SI2000. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.

Test Description

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

  1. After the ignition is turned ON, the HO2S heater heats up causing the HO2S signal voltage to either increase or decrease. This indicates that the HO2S heater is OK.

    2.

  2. If the HO2S voltage changes more than the specified value, the condition is not present.

    3.

  3. If the voltage is below the specified value, the high signal circuit, the low signal circuit, and the PCM are OK.

    4.

  4. If the voltage is above the specified value, the low signal circuit is OK.

    5.

  5. Resistance below the specified value indicates the HO2S heater is shorted.

Step

Action

Values

Yes

No

Schematic Reference: Refer to Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check-Engine Controls

2

Important: Allow the engine to cool for one-half hour before proceeding with this diagnostic. This allows the HO2S signal voltage to return to bias voltage, approximately 447 mV.

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Immediately observe the HO2S 2 voltage parameter with a scan tool for 2 minutes.

Does the HO2S 2 voltage change from bias voltage to more than or less than the specified range?

300-600 mV

Go to Step 3

Go to Step 5

3

  1. Start the engine.
  2. Allow the engine to reach operating temperature.
  3. Operate the engine at 2,000 RPM for 30 seconds.
  4. While observing the HO2S 2 voltage parameter with a scan tool, quickly cycle the throttle from closed throttle to wide open throttle, 3 times.

Did the HO2S 2 voltage change more than the specified value?

300 mV

Go to Step 4

Go to Step 5

4
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Disconnect the HO2S 2 connector.
  2. Turn ON the ignition, with the engine OFF.
  3. Connect a 3-amp fused jumper wire between the high signal circuit of the HO2S 2 on the engine harness side and a good ground.
  4. Connect a 3-amp fused jumper wire between the low signal circuit of the HO2S 2 on the engine harness side and a good ground.
  5. Observe the HO2S 2 voltage parameter with a scan tool.

Is the HO2S 2 voltage less than the specified value?

200 mV

Go to Step 9

Go to Step 6

6

  1. Remove both jumper wires from the HO2S 2 high signal and low signal circuits.
  2. Measure the voltage from the low signal circuit of the HO2S 2 on the engine harness side to a good ground with a DMM.

    3. Refer to Measuring Voltage in Wiring Systems.

Is the voltage more than the specified value?

4 V

Go to Step 7

Go to Step 8

7

Test the HO2S 2 high signal circuit for an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 16

8

Test the HO2S 2 low signal circuit for an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 16

9
  1. Remove both jumper wires from the HO2S 2 high signal and low signal circuits.
  2. Inspect the fuse that provides voltage to the HO2S 2 heater.

Is the fuse open?

--

Go to Step 12

Go to Step 10

10
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition voltage circuit of the HO2S 2 on the engine harness side with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 17

11

Connect a test lamp between the ignition voltage circuit of the HO2S 2 on the engine harness side and the heater ground circuit of the HO2S 2 on the engine harness side.

Does the test lamp illuminate?

--

Go to Step 15

Go to Step 18

12

  1. Test the ignition voltage circuit of the HO2S 2 for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
  2. Replace the fuse that provides voltage to the HO2S 2 Heater.

Did you find and correct a short to ground in the ignition voltage circuit?

--

Go to Step 21

Go to Step 13

13

Test the HO2S 2 ignition voltage circuit, sensor side, for a short to the HO2S Body. Refer to Testing for Continuity in Wiring Systems.

Did you find the condition?

--

Go to Step 19

Go to Step 14

14

Measure the resistance between the HO2S 2 ignition voltage circuit, sensor side, and the HO2S 2 heater ground circuit, sensor side with a DMM.

Does the resistance measure below the specified value?

3 ohms

Go to Step 19

Go to Diagnostic Aids

15

Inspect for poor connections at the harness connector of the HO2S 2. Refer to Testing for Intermittents and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 19

16

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

Did you find and correct the condition?

--

Go to Step 21

Go to Step 20

17

Repair the open in the HO2S 2 ignition voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 21

--

18

Repair the open in the HO2S 2 heater ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 21

--

19

Replace the HO2S 2. Refer to Heater Oxygen Sensor (HO2S) Replacement.

Did you complete the replacement?

--

Go to Step 21

--

20

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement.

Did you complete the replacement?

--

Go to Step 21

--

21
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 22

22

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK