Conditions for Clearing the MIL/DTC

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.

DTC P0140

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1	Did you perform the Diagnostic System Check-Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Start the engine. Allow the engine to idle at operating temperature. Refer to Scan Tool Data List . Clear the DTC and record the Freeze/Frame Failure Records. Quickly cycle the throttle from idle to wide open throttle 3 times while observing the HO2S 2 parameter with a scan tool. Does the voltage fluctuate above and below the specified range?	390-520 mV	Go to Step 3	Go to Step 4
3	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. 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 4	Go to Intermittent Conditions
4	Turn OFF the ignition. Disconnect the HO2S 2 connector. Turn ON the ignition, with the engine OFF. Observe the HO2S 2 parameter with a scan tool. Is the voltage more than the specified value?	500 mV	Go to Step 8	Go to Step 5
5	Measure the voltage from the HO2S 2 low signal circuit, on the engine harness side, to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage more than the specified value?	100 mV	Go to Step 9	Go to Step 6
6	Connect a 3-amp fused jumper wire between the HO2S 2 high signal circuit, on the engine harness side, and a good ground. Observe the HO2S 2 parameter with a scan tool. Is the voltage less than the specified value?	15 mV	Go to Step 7	Go to Step 10
7	Remove the jumper wire from the previous step. Connect a 3-amp fused jumper wire between the high signal circuit and low signal circuit of the HO2S 2, on the engine harness side. Observe the HO2S 2 parameter with a scan tool. Is the voltage less than the specified value?	15 mV	Go to Step 12	Go to Step 11
8	Test the HO2S 2 high signal circuit for a short to voltage. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 14
9	Test the HO2S 2 low signal circuit for a short to voltage. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 14
10	Test the HO2S 2 high signal circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 14
11	Test the HO2S 2 low signal circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 14
12	Inspect for the following that may affect the HO2S operation: NOTE: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in Cautions and Notices. HO2S contamination NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Chafed, burnt, cut, pinched, or otherwise damaged HO2S wiring Exhaust system leaks or restrictions Evaporative Emissions (EVAP) system malfunction-Inspect the EVAP control system. Refer to Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure . Incorrect fuel pressure-Refer to Fuel System Diagnosis . Did you find and correct the condition?	-	Go to Step 17	Go to Step 13
13	Test for an intermittent and for a poor connection at the HO2S 2. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 15
14	Test for shorted terminals and poor connections at the powertrain control module (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 17	Go to Step 16
15	NOTE: Refer to Heated Oxygen Sensor (HO2S) Resistance Learn Reset Notice in Cautions and Notices. Replace the HO2S 2. Refer to Heated Oxygen Sensor Replacement - Position 2 .Did you complete the replacement?	-	Go to Step 17	-
16	Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement . Did you complete the replacement?	-	Go to Step 17	-
17	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. 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 18
18	Observe the Capture Info with a scan tool. Are there any DTCs that have not diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List	System OK