The heated oxygen sensor 1 (H02S-1) is an electrical source that responds to
oxygen content in the exhaust manifold. When the sensor reaches approximately 316°C
(600°F), it produces a voltage based on the difference in oxygen between the atmosphere
and exhaust gas. The PCM sends a bias voltage (399-499 mV) on the signal
line, which is pulled up through high resistance. When the HO2S-1 is cold, it produces
no voltage and has extremely high internal resistance. The internal resistance of
the sensor is much greater than the resistance of the bias pull-up resistor. However,
when the sensor heats up, it produces voltage that overrides the bias voltage. This
voltage is read by the PCM to determine a rich/lean HO2S-1 signal used to adjust injector
pulse width. Under normal conditions, low sensor voltage means high oxygen content/lean
air-fuel mixture and vice versa. Normal sensor readings will fluctuate between 10-1065 mV.
DTC P1134 sets when the average rich to lean and lean to rich time is smaller
or greater than a certain length of time.
DTC Parameters
DTC P1134 will set if the HO2S-1 rich/lean or lean/rich transitions are outside
a calibrated range when:
| • | The engine run time is greater than 60 seconds. |
| • | The engine speed is between 1300-3000 RPM. |
| • | The TP angle is between 3-35 percent. |
| • | The ECT is greater than 70° (158°F). |
| • | The fuel level is greater than 10 percent. |
| • | The EVAP purge solenoid DC is greater than 80 percent. |
| • | The loop status is closed. |
| • | No CKP, ECT, EVAP, fuel injector, fuel tank pressure, fuel trim, IAT,
idle speed, MAP, misfire, PCM internal fault, or TP sensor DTCs have been set. |
DTC P1134 diagnostic runs once per ignition cycle for 60 seconds once
the above conditions have been met
DTC P1134 is a type B DTC.
Diagnostic Aids
Possible causes of DTC P1134:
| • | An intermittent connection or corrosion in the HO2S-1 harness connector
can set this DTC. Use the scan tool to monitor HO2S-1 voltage with the engine running
at normal operating temperature while wiggling the signal and ground wire. Make sure
the sensor is tight. |
| • | The most probable cause for DTC P1134 is contamination. Check for
obvious contamination (oil, fuel, or engine coolant) by removing the sensor. Identify
and correct the cause of the contamination if contaminated. Replace
the HO2S-1. |
