P1134 or P1154 (California W/RPO LU3)

CIRCUIT DESCRIPTION
The heated oxygen sensor (HO2S) is a sensor designed to create a voltage relative to the oxygen content in the engine exhaust stream. The control module supplies the HO2S with a signal high and low circuits. Ignition voltage and ground are supplied to the HO2S heater by independent circuits. The oxygen content of the exhaust indicates when the engine is operating lean or rich. When the HO2S detects that the engine is operating rich, the signal voltage is high, and decreases the signal voltage as the engine runs leaner. This oscillation above and below the bias voltage, sometimes referred to as activity or switching, can be monitored with the HO2S signal voltage.

The HO2S contains a heater that is necessary in order to quickly warm the sensor to operating temperature. The heater also maintains the operating temperature during extended idle conditions. The HO2S needs to be at a high temperature in order to produce a voltage. When the HO2S reaches operating temperature, the control module monitors the HO2S bias, or reference, voltage. The control module also monitors the HO2S signal voltage for Closed Loop fuel control. During normal Closed Loop fuel control operation, the control module will add fuel, or enrich the mixture, when the HO2S detects a lean exhaust content. The control module will subtract fuel, or lean out the mixture, when the HO2S detects a rich exhaust condition.

This DTC determines if the difference in transition times from lean-to-rich or rich-to-lean has exceeded a maximum ratio. The powertrain control module (PCM) monitors the time needed for the HO2S to transition from more than 600 mV to less than 300 mV and vice versa. If either of these times is longer than the other by a calibrated ratio, this DTC is set.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1404, or P1441 are not set.
^ The loop status is Closed.
^ The engine run time is more than 160 seconds.
^ The engine speed is between 1,300-3,000 RPM.
^ The engine coolant temperature (ECT) is more than 57°C (135°F).
^ The mass airflow (MAF) sensor is between 20-45 g/s.
^ The throttle position (TP) sensor is more than 5 percent.
^ The ignition 1 signal is between 9-18 volts.
^ The fuel tank level remaining is more than 10 percent.
^ Intrusive tests are not in progress.
^ Scan tool output controls are not active.
^ The evaporative emissions (EVAP) purge solenoid command is more than 1 percent.
^ The above conditions are met for 50 seconds.

CONDITIONS FOR SETTING THE DTC
The HO2S transition time ratio is not within a 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.

TEST DESCRIPTION

DTC P1134 Or P1154 (California W/RPO LU3) - Steps 1-8:

DTC P1134 Or P1154 (California W/RPO LU3) - Steps 9-16:

DTC P1134 Or P1154 (California W/RPO LU3) - Steps 17-25:

The numbers below refer to the step numbers on the diagnostic table.
2. After the ignition is turned ON, the HO2S heater heats up causing the HO2S signal voltage to either increase or decrease. This indicates that the HO2S heater is OK.
3. If the HO2S voltage is varying outside the specified range, the condition is not present.
6. If the test lamp illuminates, the low reference circuit between the HO2S and PCM terminal C1-63 is OK and the PCM low reference terminal is OK.
7. If the voltage is below the specified value, the high signal circuit, the low reference circuit, and the PCM are OK.
14. The opposite bank HO2S must be disconnected to isolate a short to ground in the HO2S heater ignition 1 voltage circuit.
16. Resistance within the specified range indicates the HO2S heater is OK.

For a description of the RPO Code(s) shown in this article or any of the images therein, refer to the RPO Code List found at Vehicle/Application ID". RPO Codes