P0030

CIRCUIT DESCRIPTION
The heating elements inside the heated oxygen sensors (HO2S) minimize the time required for the sensors to reach operating temperature and then provide an accurate voltage signal. The PCM controls the HO2S heater operation with a low side driver. The HO2S 1 heater diagnostic monitors the current draw through a high side driver that also supplies power to the HO2S bank 1 sensor 1 heater. If the powertrain control module (PCM) detects that the HO2S bank 1 sensor 1 heater high control circuit condition is incorrect, DTC P0030 will set.

CONDITIONS FOR RUNNING THE DTC
- The system voltage is between 9-18 volts.
- The ignition is ON.

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.

TEST DESCRIPTION

Steps 1-4:

Steps 5-10:

Steps 11-15:

The numbers below refer to the step numbers on the diagnostic table.
3. This step determines if the PCM is supplying voltage from the high side driver through the HO2S bank 1 sensor 1 heater high control circuit.
4. This step determines if ignition 1 voltage is being supplied from the underhood fuse block. The battery voltage in this step indicates a functional low control circuit for both front sensors.
7. The bank 1 sensor 1 and the bank 2 sensor 1 low control circuits are internally connected within the PCM. A short to ground between the HO2S bank 2 sensor 1 low control circuit and the PCM will set this DTC.