GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Seville - RHD 🢒 DTC 🢒 DTC P0030

Circuit Description

The heated oxygen sensor (HO2S) heater is a device used to reduce the time that the sensor takes to go active. The powertrain control module (PCM) uses a high side driver in order to apply ignition voltage to the bank 1 sensor 1 heater, and uses a low side driver (ODM) in order to supply the ground path. The PCM monitors the high side driver for circuit conditions that are incorrect for the commanded state of the driver. If the PCM detects an improper circuit condition in the high side driver, the diagnostic trouble code (DTC) 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 in the high side driver for HO2S bank 1 sensor 1.

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

Notice: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:

   • The PCM harness connectors
   • The electrical center fuse/relay cavities
   • The component terminals
   • The component harness connector
Using this kit will prevent damage caused by the improper probing of connector terminals.

If the condition is intermittent, refer to Intermittent Conditions in Symptoms.

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, one of the heater low circuits is grounded. An internal HO2S condition can also cause all DTCs to set.

    2.

  2. This step determines if the bank 1 sensor 1 heater high circuit is shorted to a ground.

    3.

  3. The bank 1 sensor 1 and the bank 2 sensor 1 are internally connected within the PCM. If the voltage measurement is within the specified range, the bank 2 sensor 1 is causing the condition.

Step

Action

Values

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 P0030, P0036, P1031, and P1032

Are all 4 DTCs set?

--

Go to Step 11

Go to Step 3

3

Did DTC P0030, P1031, or P1032 set?

--

Go to Step 7

Go to Step 4

4

Is DTC P0030 set?

--

Go to Step 5

Go to Intermittent Conditions

5

  1. Turn OFF the ignition.
  2. Disconnect the HO2S bank 1 sensor 1 harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a DMM, measure the voltage at the HO2S bank 1 sensor 1 heater high control circuit.

Is the voltage more than the specified value?

10 V

Go to Step 15

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector. Refer to Powertrain Control Module Replacement .
  3. Test the HO2S bank 1 sensor 1 heater high control circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

7
  1. Turn OFF the ignition.
  2. Disconnect the HO2S bank 1 sensor 1 harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a DMM, measure the voltage at the HO2S bank 1 sensor 1 heater low control circuit.

Is the voltage more than the specified value?

10 V

Go to Step 15

Go to Step 8

8

  1. Turn OFF the ignition.

    2. Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

  2. Disconnect the HO2S bank 2 sensor 1 harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a DMM, measure the voltage at the HO2S bank 1 sensor 1 heater low control circuit.

Is the voltage within the specified range?

1.2-1.7 V

Go to Step 14

Go to Step 9

9

  1. Turn OFF the ignition.
  2. Disconnect the PCM harness connector. Refer to Powertrain Control Module Replacement .
  3. Test the HO2S bank 1 sensor 1 heater low control circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

 

Go to Step 18

Go to Step 10

10

Test the HO2S bank 2 sensor 1 heater low control circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

11
  1. Turn OFF the ignition.
  2. Remove the HO2S fuse from the underhood electrical center.
  3. With a test lamp connected to B+, probe the fuse terminal closest to the windshield.
  4. Observe the test lamp as you disconnect the HO2S bank 2 sensor 1 harness connector. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

Does the test lamp turn OFF?

--

Go to Step 14

Go to Step 12

12

Observe the test lamp as you disconnect the HO2S bank 1 sensor 2 harness connector. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 .

Does the test lamp turn OFF?

--

Go to Step 16

Go to Step 13

13

Repair the short to ground in the ignition 1 voltage circuit to the HO2S sensors.

Did you complete the repair?

--

Go to Step 18

--

14

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

Did you complete the replacement?

--

Go to Step 18

--

15

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

Did you complete the replacement?

--

Go to Step 18

--

16

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

Did you complete the replacement?

--

Go to Step 18

--

17

Replace the PCM. Refer Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 18

--

18
  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 19

Go to Step 2

19

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