DTC P0139 or P0159. Saturn L300/LW300 2005

For 1990-2009 cars only

Makes 🢒 Saturn 🢒 2005 🢒 L300/LW300 🢒 Brakes 🢒 Park Brake 🢒 DTC P0139 or P0159

Engine Controls Component Views
Engine Controls Schematics

Circuit Description

The heated oxygen sensor (HO2S) produces a voltage that varies between 100-900 mV under normal operating conditions. The engine control module (ECM) produces a bias voltage on the HO2S signal circuit of 420-480 mV. The reference ground for the sensor is provided through the ECM. The ECM monitors the signal voltage to determine if the exhaust is lean or rich. The oxygen sensor voltage is high when the exhaust is rich, and low when the exhaust is lean. The ECM constantly monitors the HO2S signal during the Closed Loop operation. If the ECM forces a lean or rich status and detects an HO2S voltage that is not properly correlated to the commanded rich or lean state, DTC P0139 will set for bank 1 sensor 2 or DTC P0159 will set for bank 2 sensor 2.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•	DTC P0139 HO2S Slow Response Bank 1 Sensor 2

•	DTC P0159 HO2S Slow Response Bank 2 Sensor 2

Conditions for Running the DTC

•	The bank 1 sensor 2 or bank 2 sensor 2 Loop Status is Closed.

•	The Battery Voltage parameter is more than 11 volts.

•	The calculated catalytic converter temperature is less than 940°C (1,724°F).

•	DTC P0139 and P0159 run continuously once the above conditions are met.

Conditions for Setting the DTC

•	The ECM detects that the HO2S parameter is stuck above or below 350 mV for longer than 1,000 seconds.

•	The ECM detects that the HO2S parameter is more than 200 mV for longer than 5 seconds during a decel fuel cutoff condition.

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.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

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

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

Operate the engine at normal operating temperature.
Quickly cycle the throttle from closed throttle to wide open throttle 3 times while observing the affected HO2S voltage parameter with a scan tool.

Does the affected HO2S voltage parameter react immediately to the above action?

Go to Step 3

Go to Step 4

Observe the Freeze Frame/Failure Records for this DTC.
Turn OFF the ignition for 90 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 affected heated oxygen sensor (HO2S).
Turn ON the ignition, with the engine OFF.
Observe the voltage parameter with a scan tool.

Is the HO2S voltage parameter above the specified value?

525 mV

Go to Step 5

Go to Step 7

Measure the voltage from the HO2S 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?

50 mV

Go to Step 9

Go to Step 6

Measure the voltage from the HO2S high 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?

550 mV

Go to Step 10

Go to Step 15

Connect a 3-amp fused jumper wire between the HO2S high signal circuit on the engine harness side and a good ground.
Observe the HO2S voltage parameter with a scan tool.

Is the voltage less than the specified value?

25 mV

Go to Step 8

Go to Step 11

Remove the jumper wire from the previous step.
Connect a 3-amp fused jumper wire between the HO2S high signal circuit on the engine harness side and the HO2S low signal circuit on the engine harness side.
Observe the HO2S voltage parameter with a scan tool.

Is the voltage less than the specified value?

25 mV

Go to Step 13

Go to Step 12

Test the HO2S low signal circuit for a short to voltage or a short to the heater low control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

Test the HO2S high signal circuit for a short to voltage or a short to the heater low control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

Test the HO2S high signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

Test the HO2S low signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

The HO2S 2 is detecting a rich or lean exhaust condition or may be contaminated. Inspect for one of the following conditions:

•	HO2S connector water intrusion

•	A silicon-contaminated HO2S 2

•	Fuel-contaminated engine oil

•	Incorrect fuel pressure--Refer to Fuel System Diagnosis .

•	A leaking fuel pressure regulator--Refer to Fuel System Diagnosis .

•	Rich fuel injectors--Refer to Fuel Injector Balance Test with Special Tool .

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

Did you find and correct the condition?

Go to Step 17

Go to Step 15

Test for shorted terminals and poor connections at the engine control module (ECM). 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

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 17

Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 17

Clear the DTCs with a scan tool.
Turn OFF the ignition for 90 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

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK