GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Seville - RHD 🢒 DTC 🢒 DTC P0036

Circuit Description

The heated oxygen sensor (HO2S) heater is a device used to reduce the time that the sensor takes to go active. The bank 1 sensor 2 heater helps to maintain the sensor at the proper temperature for catalyst testing, and additional adjustments to fuel trim. The bank 1 sensor 2 heater receives power through a fused ignition circuit. The powertrain control module (PCM) turns the heater ON, and OFF using a low side driver (ODM) located within the PCM. The PCM monitors the low side driver for circuit conditions that are incorrect for the commanded state of the low side driver. If the PCM detects an incorrect circuit condition, diagnostic trouble code (DTC) P0036 will set.

Conditions for Running the DTC

The system voltage is between 9-18 volts.

Conditions for Setting the DTC

The PCM detects an incorrect circuit condition for the commanded state of the low side driver.

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

If the condition is intermittent, refer to Intermittent Conditions .

Test Description

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

  1. This step isolates the condition. If all DTCs are set, this indicates that one of the heater low circuits are grounded. An internal HO2S condition can also cause all DTCs to set.

    2.

  2. This step isolates the condition. If DTC P0036 is set without the other control circuit faults, the condition is present only in the HO2S bank 1 sensor 2 heater low control circuit.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, clear the DTCs.
  3. With a scan tool, observe the DTC information for 30 seconds.

Are DTCs P0030, P0036, P1031, and/or P1032 set?

Go to DTC P0030

Go to Step 3

3

  1. Start the engine and bring to operating temperature.
  2. With a scan tool, clear the DTCs.
  3. With a scan tool, observe the DTC information for 30 seconds.

Does DTC P0036 set?

Go to Step 4

Go to Intermittent Conditions

4

  1. Turn OFF the ignition.
  2. Disconnect the HO2S bank 1 sensor 2 harness connector. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 .
  3. Turn ON the ignition, with the engine OFF.
  4. With a test lamp connected to ground, probe the ignition supply voltage circuit at the HO2S bank 1 sensor 2 harness connector.

Does the test lamp illuminate?

Go to Step 5

Go to Step 11

5

With a test lamp connected to B+, probe the HO2S bank 1 sensor 2 heater low control circuit.

Does the test lamp illuminate?

Go to Step 6

Go to Step 7

6
  1. Leave the test lamp connected between B+ and the HO2S bank 1 sensor 2 heater low control circuit.
  2. Turn OFF the ignition.
  3. Disconnect the PCM connectors. Refer to Powertrain Control Module Replacement .
  4. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 13

Go to Step 15

7
  1. Leave the test lamp connected between B+ and the HO2S bank 1 sensor 2 heater low control circuit.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the HO2S heater driver 4 ON and OFF.

Does the test lamp turn ON and OFF?

Go to Step 12

Go to Step 8

8

Test the HO2S bank 1 sensor 2 heater low control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 9

9

Test the HO2S bank 1 sensor 2 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 16

Go to Step 10

10

Test the HO2S bank 1 sensor 2 heater low control circuit for poor connections at 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 16

Go to Step 15

11

Repair the open in the ignition supply voltage circuit to the HO2S bank 1 sensor 2.

Did you complete the repair?

Go to Step 16

--

12

Test for poor connections at the HO2S bank 1 sensor 2 connector. 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 16

Go to Step 14

13

Repair the short to ground in the HO2S bank 1 sensor 2 heater low control circuit.

Did you complete the repair?

Go to Step 16

--

14

Replace HO2S bank 1 sensor 2. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 .

Did you complete the replacement?

Go to Step 16

--

15

Replace the PCM. Refer Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 16

--

16
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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 17

Go to Step 4

17

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