Closed Loop Lambda Control - Enable Conditions

Closed loop lambda control is enabled (with a delay) at the start of a driving cycle and can be temporarily or permanently deactivated during the driving cycle. The turn-on delay at start of a driving cycle is described by the following enable conditions:

• the upstream oxygen sensor operability is detected i.e. the upstream HO2'S operating temperature has been reached
• certain time after engine start has expired
• Closed loop lambda operation is disabled, if the following conditions are met:
  • when catalyst overheating prevention is active
  • sensor heater failure present in the current d.c.
  • sensor failure present in the current d.c.
  • misfire detected in the current d.c.
  • the purge valve plausibility check is active
  • secondary air system is active