P1134
DTC P1134CIRCUIT 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 of the exhaust stream. When the vehicle is first started, the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference or bias voltage of about 450 mV. The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once the sensor reaches operating temperature. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature, and provide an accurate voltage signal. The PCM monitors the rich-to-lean and lean-to-rich transition time. A transition is defined as the HO2S voltage changing from above 598 mV to below 300 mV and from below 300 mV to above 598 mV. If the PCM detects the difference between the rich-to-lean average transition time and the lean-to-rich average transition time is more than a specified value. DTC P1134 will set.
Each HO2S 1 has the following circuits:
- An HO2S 1 high signal circuit
- An HO2S 1 low signal circuit
- An HO2S 1 heater ignition voltage circuit
- An HO2S 1 heater low control circuit
- An HO2S low reference circuit
CONDITIONS FOR RUNNING THE DTC
- DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0205, P0206, P0442, P0443, P0446, P0449, P0455, P0496, P1106, P1107, P1111, P1112, P1114, P1115 are not set.
- DTCs P0136, P0401, and P0420 passed.
- The vehicle is not in Park, Reverse, or Neutral.
- The Engine Run Time parameter is more than 60 seconds.
- The MAF Sensor parameter is between 13-30 g/s.
- The TP Sensor parameter is varying less than 2 percent.
- The Engine Speed parameter is between 1,000-3,000 RPM.
- The ECT Sensor parameter is more than 65°C (149°F).
- The Loop Status parameter is closed.
- The HO2S Heater Command parameter is ON.
- The EVAP Purge Solenoid Command parameter is more than 0 percent.
- The system voltage is between 9-18 volts.
- The above conditions have been met for 2 seconds.
CONDITIONS FOR SETTING THE DTC
The PCM detects that the average transition time difference is not within a calibrated range during a 90 second monitoring period.
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
