GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2004 🢒 L300/LW300 🢒 DTC 🢒 DTC P0135 or P0141

Circuit Description

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the powertrain control module (PCM). The PCM monitors the current flow through the heater for diagnosis.

If the PCM detects that the HO2S heater current is outside a specified range, DTC P0135 sets for HO2S 1 or DTC P0141 sets for HO2S 2.

Conditions for Running the DTC
    • DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0128, P0201-P0204, P0300, P0301-P0304, P0315, P0336, P0442, P0446, P0452, P0453, P0455, P0496, P0506, P0507, P0601, P0602, P1621 are not set.
    • The ignition 1 signal parameter is between 11-17 volts.
    • The engine coolant temperature (ECT) sensor parameter is more than 70°C (158°F).
    • The fuel level sensor parameter is more than 10 percent.
    • The engine run time parameter is more than 60 seconds.

Conditions for Setting the DTC
    • The PCM detects that the affected HO2S heater current is less than 0.217 amps or more than 1.56 amps.
    • The above condition is met for 200 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.

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls 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
  1. Start the engine.
  2. Command the affected heated oxygen sensor (HO2S) heater ON with a scan tool.
  3. Wait 15 seconds to allow the HO2S heater current to stabilize.
  4. Observe the HO2S heater current parameter with a scan tool.

Is the HO2S heater current parameter within the specified range?

0.217-1.56 A

Go to Step 3

Go to Step 4

3

  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 4

Go to Intermittent Conditions

4

Inspect the EIS fuse.

Is the EIS fuse open?

--

Go to Step 5

Go to Step 6

5

Test the ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 8

6
  1. Disconnect the affected HO2S.
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the ignition 1 voltage circuit of the HO2S connector on the vehicle harness side with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 19

7

  1. Connect a test lamp between the ignition 1 voltage circuit of the HO2S connector on the vehicle harness side and the HO2S heater low control circuit of the HO2S connector on the vehicle harness side.
  2. Command the HO2S heater ON and OFF with a scan tool.

Does the test lamp turn ON and OFF with each command?

--

Go to Step 9

Go to Step 11

8

Test the ignition 1 voltage circuit on the sensor side of the HO2S connector for a short to ground. Refer to Circuit Testing in Wiring Systems.

Is the sensor shorted to ground?

--

Go to Step 20

Go to Intermittent Conditions

9
  1. Measure the voltage from the ignition 1 voltage circuit of the HO2S connector, on the vehicle harness side, to a good ground with a DMM.
  2. Note this value as "supply voltage".
  3. Set the DMM to amps and connect a test lamp and a DMM in series between the ignition 1 voltage circuit and the heater low control circuit of the HO2S connector, on the vehicle harness side.
  4. Command the HO2S heater ON with a scan tool.
  5. Observe the DMM amperage and note as "current draw".
  6. Remove the DMM and connect the test lamp between the ignition 1 voltage circuit and the heater low control circuit of the HO2S connector, on the vehicle harness side.
  7. Set the DMM to volts and connect the DMM in parallel between the ignition 1 voltage circuit of the HO2S connector, on the vehicle harness side, and a good ground.
  8. Command the HO2S heater ON with a scan tool.
  9. Observe the voltage and note as "load voltage drop".
  10. Subtract the load voltage drop from the supply voltage and divide this result by the current draw in order to calculate the resistance in the ignition 1 voltage circuit.

Is the calculated resistance more than the specified value?

5 ohms

Go to Step 18

Go to Step 10

10
  1. With the test lamp still connected, connect a DMM in parallel between the heater low control circuit of the HO2S connector, on the vehicle harness side, and a good ground.
  2. Command the HO2S heater ON with a scan tool.
  3. Observe the voltage and note as "heater low control circuit voltage drop".
  4. Divide the heater low control circuit voltage drop by the current draw in order to calculate the resistance in the heater low control circuit.

Is the calculated resistance more than the specified value?

5 ohms

Go to Step 17

Go to Step 15

11

Does the test lamp remain illuminated with each command?

--

Go to Step 12

Go to Step 13

12

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

Did you find and correct the condition?

--

Go to Step 22

Go to Step 16

13

Test the HO2S heater low control 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 22

Go to Step 14

14

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

Did you find and correct the condition?

--

Go to Step 22

Go to Step 16

15

Test for shorted terminals and for poor connections at 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 22

Go to Step 20

16

Test for shorted terminals and for 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 22

Go to Step 21

17

Test the HO2S heater low control circuit for resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 16

18

Repair the circuit with high resistance. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 22

--

19

Repair the open or high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 22

--

20

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

Did you complete the replacement?

--

Go to Step 22

--

21

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 22

--

22

Were you sent to this diagnostic from DTC P0134?

--

Go to Step 18 in DTC P0134

Go to Step 23

23

Were you sent to this diagnostic from DTC P0140?

--

Go to Step 18 in DTC P0140

Go to Step 24

24
  1. Replace the EIS fuse if necessary.
  2. Clear the DTCs with a scan tool.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.
  5. 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 25

25

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