911 Carrera 4 Cabriolet (996) F6-3.4L (1999)
Oxygen Sensor: Testing and Inspection
OXYGEN SENSOR MONITORING
General Description
The response rate of the upstream oxygen sensor is monitored by measuring the period of the lambda control oscillations. This measurement is
performed under the following conditions.
manual transmission
automatic transmission
engine speed:
1,400 - 2,600 rpm and
1,200 - 2,200 rpm
load:
0.7 [<] IL [<] 1.9 ms and
0.7 [<] TL [<]2.2 ms
(catalyst temperature is[>] 352 °C)
Monitoring Structure
Oxygen Sensor Monitoring
Monitoring of electrical faults of sensors upstream and downstream of catalyst:
Implausible voltages
-
ADC-voltages exceeding the maximum threshold UMAX are caused by a short circuit to Ubat
-
ADC-voltages falling below the minimum threshold UMIN are caused by short circuit of sensor signal or sensor ground to EMC ground
Implausible course of sensor voltage
A open circuit of the sensor upstream catalyst can be detected, if the ADC-voltage remains in a specified range after the sensor has been heated.
Flow chart of monitoring function (oxygen sensor)