P0135
CIRCUIT DESCRIPTIONThe heated oxygen sensor (HO2S) heater is used in order to reduce the time that the sensor takes to go active. The powertrain control module (PCM) controls the HO2S heaters using a high side driver, two low side drivers, and a current monitoring driver. The current monitoring driver test the condition of the heaters. The high side driver provides the HO2S bank 1 sensor 1 heater with ignition voltage. A fused ignition feed provides bank 1 sensor 2, and bank 2 sensor 1 with ignition voltage. HO2S bank 1 sensor 1, and bank 2 sensor 1 receives ground through one of the low side drivers. While HO2S bank 1 sensor 2 receives ground through a separate low side driver.
With the engine running, the PCM turns ON the high side, and the low side drivers to warm-up the oxygen sensors. When the proper conditions are present, the PCM keeps the high side driver ON, turns ON the current monitor driver, and then turns OFF the warm-up driver. This allows the PCM to record a total current value for both of the fuel control heaters. If the test conditions remain stable, the PCM enters the second stage of the test. During this stage, the PCM keeps the current monitor ON, and turns OFF the high side driver. This allows the PCM to record a current value for the bank 2 sensor 1 heater circuit. The PCM subtracts the bank 2 sensor 1 current value from the total current value to determine the current value for bank 1 sensor 1. If the PCM detects a bank 1 sensor 1 current value outside the calibrated range, the DTC will set.
CONDITIONS FOR RUNNING THE DTC
^ DTCs P0030, P1031, or P1032 are not set.
^ The system voltage during the current measurement is steady within 1 volt of the actual system voltage.
^ The engine speed is between 500-3,000 RPM.
^ The engine run time is more than 180 seconds.
^ The mass air flow (MAF) is between 4-30 g/s.
^ The HO2S overtemp control is not active.
^ All of the above conditions are met for 3 seconds.
CONDITIONS FOR SETTING THE DTC
The PCM detects a bank 1 sensor 1 current value outside the calibrated range.
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
NOTE: Refer to Heated Oxygen Sensor (HO2S) Wire Repair Notice in Service Precautions.
If the condition is intermittent, refer to Intermittent Conditions. Intermittent Conditions
TEST
