DTC P0140 or P0160. Chevrolet Epica 2005

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.5L (LBK) 🢒 DTC P0140 or P0160

Circuit Description

The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S 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 ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range.

The HO2S utilizes the following circuits:

•	A signal circuit

•	A low reference circuit

•	An ignition 1 voltage circuit

•	A heater control circuit

If the ECM detects that the HO2S voltage does not increase after exiting decel fuel cut-off (DFCO) mode, the DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTCs:

•	DTC P0140 HO2S Insufficient Activity Bank 1 Sensor 2

•	DTC P0160 HO2S Insufficient Activity Bank 2 Sensor 2

Conditions for Running the DTC

•

DTCs P0030, P0031, P0050, P0051, P0101, P0102, P0103, P0111, P0112, P0113, P0116, P:0117, P0118, P0119, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0134, P0151, P0152, P0154, P0171, P0172, P0174, P0175, P0261, P0262, P0263, P0264, P0265, P0266, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0300, P0400, P0401, P0402, P0403, P0404, P0405, P0406, P0441, P0442, P0444, P0445, P0455, P0456, P0501, P1171, P1172, P1174, P1175, P1504 are not set.

•	The H02S test is ran when the following conditions are met during DFCO mode:

-	The engine is operating.

-	The ignition 1 voltage is more than 10 volts.

-	The fuel system is in closed loop.

-	The calculated airflow is more than 40 g/s.

-	The vehicle speed is more than 5 Km/h (3 mph)

•	The DTCs run continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the HO2S voltage does not increase more than 25 mV after exiting DFCO mode for 1 second.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•	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.

Test Description

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

This step determines if the condition is present. This test may take 5-10 minutes for the diagnostic to run.

This step tests the HO2S signal and the low reference circuit for an high resistance. The HO2S voltage should go low.

An exhaust leak 6-12 inches away from the HO2S can cause a DTC to set.

Certain RTV silicone gasket materials release vapors that can contaminate the HO2S. Silicone in the fuel can also cause silicone contamination. If the sensors appear contaminated by silicone, and if all the silicone sealant is a non-silicone base, advise the customer to try a different fuel company. A missing fuel filler restrictor indicates that the customer may have used leaded fuel.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: If any DTCs are set, except for P0140 or P0160, refer to those DTCs before proceeding with this diagnostic table.

Allow the engine to reach the normal operating temperature.
Operate the vehicle within the parameters specified in Conditions for Running the DTC.
Observe the diagnostic trouble code (DTC) information with a scan tool.

Did the DTC P0140 or P0160 fail this ignition?

Go to Step 4

Go to Step 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

Turn OFF the ignition.
Disconnect the harness connector of the affected heated oxygen sensor (HO2S). For the H02S location, refer to Engine Controls Component Views .
Connect a 3-ampere fused jumper wire between the signal circuit and the low reference circuit of the HO2S.
Start the engine.
Observe the HO2S voltage parameter with a scan tool.

Is the voltage less than the specified value?

20 mV

Go to Step 8

Go to Step 5

Connect a 3-ampere fused jumper wire between the HO2S signal circuit and a good ground.
Observe the HO2S voltage parameter with a scan tool.

Is the voltage less than the specified value?

20 mV

Go to Step 7

Go to Step 6

Test the HO2S signal circuit for high resistance. 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

Test the HO2S low reference circuit for high resistance. 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 an exhaust leak near the oxygen sensor.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

Inspect or test for the following conditions:

•	The HO2S is securely installed.

•	Inspect for corrosion on the HO2S terminals.

•	Inspect the terminal tension at the HO2S and at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

•	Inspect the HO2S wiring for damage. Refer to Wiring Repairs in Wiring Systems.

•	Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Inspect for the correct RTV sealant.

•	Inspect for engine oil consumption. Refer to Oil Leak Diagnosis in Engine Mechanical - 2.5L (LBK).

•	Inspect for engine coolant consumption. Refer to Loss of Coolant in Engine Cooling.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

Test for shorted terminals and for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

Replace the appropriate HO2S.

Did you complete the replacement?

Go to Step 13

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

Go to Step 13

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 14

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