This function is used to test the lambda probe before the catalytic converter.
Test prerequisites:
Engine running.
No faults in the system.
Engine temperature above 80 °C.
No leaks in the exhaust system.
All consumers inactive.
Procedure:
Choose the function: "Lambda probe before catalytic converter".
Press and hold down the brake pedal. The engine control unit increases the engine speed to about 1100-1300 rpm.
The temperature of the catalytic converter must be at least 400 °C.
The diagnostic status field changes from "Test off" to "Test on".
Maintain the engine speed until the diagnostic status field changes from "Test on" to "B1-S1 OK" or "B1-S1 not OK".
Read the oscillation curve of the lambda probe before the catalytic converter. Prescribed value 0.7-2.00.