Oxygen Sensor Heating

The MS41.1 Control Module uses internal final stage control for O2 sensor heating similar to the function introduced on the Bosch M5.2 system. OBD II requires that the O2 sensor heating function be monitored for operation. The use of the MS41.1 Control Module final stage control allows this monitoring function.

The four O2 sensors heating circuits receive operating power from the ECM relay when KL 15 is switched ON. Each of the sensor heaters are controlled through separate final stages. The sensor heaters are controlled with a pulsed square wave voltage during a cold start. This allows the sensors to be brought up to operating temperature without the possibility of thermal shock. The duty cycle is then varied to maintain the heating of the sensors.