DTC P0138 or P0158. Chevrolet Corvette 2002

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2002 🢒 Corvette 🢒 Engine 🢒 Engine Controls - 5.7L 🢒 DTC P0138 or P0158

Circuit Description

The powertrain control module (PCM) supplies a voltage of approximately 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage from approximately 1,000 mV when the exhaust is rich, through approximately 10 mV when the exhaust is lean.

The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the period of time in which the HO2S voltage was out of range. The PCM 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 PCM monitors the HO2S voltage for being fixed above a predetermined voltage. If the PCM detects the voltage is above a predetermined voltage, a DTC sets.

Conditions for Running the DTC

•	DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0200, P0300, P0410, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1415, P1416, P1441, P1514, P1515, P1516, P1517, or P1518 are not set.

•	The ignition 1 signal is between 9-18 volts.

•	The fuel tank level remaining is more than 10 percent.

•	The loop status is Closed.

•	Intrusive tests are not in progress.

•	Scan tool output controls are not active.

Rich Test Enable

•	The air fuel ratio is between 14.5:1-14.7:1.

•	The throttle position (TP) indicated angle is between 3-70 percent more than the value observed at idle.

Decel Fuel Cut-off Test Enable

•	Decel fuel cut-off is active.

•	The above condition is met for 10 seconds.

Conditions for Setting the DTC

Rich Test

The HO2S voltage is more than 930 mV for 200 seconds.

Decel Fuel Cut-off Test

The HO2S voltage is more than 480 mV for 5 seconds.

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.

Diagnostic Aids

Important:

•

Before you service the PCM and throttle actuator control (TAC) module, remove any debris from the module connector surfaces. Inspect the module connector gaskets when you diagnose or replace the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the modules.

•	For any test that requires probing the PCM or a component harness connector, use the J 35616 Connector Test Adapter Kit . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

•	Inspect the HO2S electrical connections for evidence of water intrusion. Water in the connector causes the B+ supply to the heater to bleed over to the signal circuit.

•	Inspect the fuel pressure--The system goes rich if the pressure is too high. The PCM compensates for some increase. If the fuel pressure is too high, a DTC may set. Refer to Fuel System Diagnosis .

•	Inspect for rich injectors--Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool .

•	Inspect for leaking injectors--Refer to the Fuel System Diagnosis .

•	Inspect for fuel saturation in the evaporative emissions (EVAP) canister purge. If the canister is full of fuel, inspect the canister control and the hoses. Refer to Evaporative Emission Control System Description .

•

Inspect the mass air flow (MAF) sensor. Disconnect the MAF sensor and determine if the rich condition is corrected. If the condition is corrected, inspect the sensor for proper installation. If the sensor is properly installed, replace the MAF sensor. If the MAF sensor is installed backwards, the system goes rich. The plastic portion of the sensor has arrows indicating proper air flow direction. The arrows must point toward the engine.

•	An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provide the supply of oxygen. Inspect the HO2S wires and the connections for breaks or for contamination. Refer to Wiring Repairs in Wiring Systems.

•	For an intermittent condition, refer to Intermittent Conditions .

Test Description

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

This DTC also sets during a deceleration fuel cut-off. Inspect for conditions such as leaking or stuck injectors, which could cause a rich exhaust during a deceleration.

The engine must be at the normal operating temperature before you perform this test.

Using the Freeze Frame and/or Failure Records data may help to locate an intermittent condition. If you cannot duplicated the DTC, the information included in the Freeze Frame/Failure Records data can help to determine how many miles have occurred since the DTC set. You can also use the Fail Counter and Pass Counter in order to determine the number of ignition cycles in which the diagnostic reported a pass and/or a fail. Operate the vehicle within the same Freeze Frame conditions that you observed, including the RPM, the vehicle load, the vehicle speed, and the temperature. This procedure will isolate when the DTC failed.

If the voltage remains high, this indicates that the signal circuit is shorted to a voltage.

Step

Action

Value(s)

Yes

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to

Diagnostic System Check - Engine Controls

Start and run the engine until normal operating temperature is reached.
With a scan tool, observe the HO2S voltage for the sensor that applies to this DTC.

Is the HO2S voltage more than the specified value?

930 mV

Go to Step 5

Go to Step 3

Change the throttle position more than 5 percent within 1 second, 6 times.
Observe the affected HO2S voltage with a scan tool.

Is the HO2S voltage within the specified range?

350-550 mV

Go to DTC P0140 or P0160

Go to Step 4

Observe the Freeze Frame/Failure Records data for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, or as close to the Freeze Frame/Failure Records data that you observed.

Does the DTC fail this ignition?

Go to Step 5

Go to Diagnostic Aids

Turn OFF the ignition.
Disconnect the HO2S connector for the sensor that applies to this DTC.
Jumper the HO2S low signal circuit terminal on the engine harness side to a known good ground.
Turn ON the ignition, with the engine OFF.
Observe the HO2S voltage with a scan tool.

Is the HO2S voltage within the specified range?

350-550 mV

Go to Step 6

Go to Step 7

The HO2S may be detecting a rich exhaust condition or may be contaminated. Check for the following conditions:

•	Water intrusion into the HO2S connector

•	Silicone contamination of the HO2S

•	Engine oil contaminated by fuel

•	Incorrect fuel pressure

•	Rich fuel injectors

•	Inaccurate MAF sensor

•	EVAP canister purge condition

Repair any of the above or similar engine conditions as necessary.

Did you find and correct the condition?

Go to Step 12

Go to Step 8

Important: The sensor may be damaged if the circuit is shorted to a voltage source.

Turn OFF the ignition.
Disconnect the PCM connector that contains the HO2S high signal circuit. Refer to Powertrain Control Module Replacement .
Turn ON the ignition with the engine OFF.
Test the HO2S high signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 9

Inspect for poor connections at the harness connector of the HO2S. 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 12

Go to Step 10

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 12

Go to Step 11

Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 .

Did you complete the replacement?

Go to Step 12

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 12

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 as specified in the supporting text.

Does the DTC run and pass?

Go to Step 13

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK