Diagnosis of Lambda Sensor Downstream Catalyst

Diagnosis of Lambda Sensor Downstream Catalyst (911 Turbo)







Diagnosis of Lambda Sensor Downstream Catalyst (911 Carrera, Boxster, Boxster S)







Aging Monitor of the Rear Lambda Sensor

Oscillation Check
The function checks whether the sensor output voltage of the rear lambda sensor (Nernst type) always remains above or below a specified threshold.

If the rear closed loop lambda control, which uses the sensor signal of the rear lambda sensor, is active the lambda sensor voltage must cross a threshold at least once within a specified period of time (approximately 65 seconds).

If the sensor voltage remains above or below the threshold, a test function will be started, the system switches to rich or lean operation (Delta(Lambda(rich)) = 10 % , Delta(Lambda(lean)) = 7% ). If the voltage was above the threshold, there will be a lean operation and vice versa. This function is interrupted by fuel cut-off, by very low load conditions, etc. If the sensor voltage reacts appropriately (crossing the threshold in the expected direction), the sensor is o.k. If there is no reaction, the sensor is judged as faulty, an error flag will be set and the rear closed loop control will be switched off.

Aging Monitoring of Rear Lambda Sensor - Oscillation Check