GF07.61-P-3025V O2 Sensor Heater Function

GF07.61-P-3025V O2 Sensor Heater Function







The purpose of the O2 sensor heater is to rapidly heat up the O2 sensors to their operating temperature while preventing damage to the sensor ceramic as a result of controlled heating.

O 2 sensor downstream TWC (Lambda discrete sensor)
The sensor heater of the O2 sensors downstream of TWC is actuated via GND and pulsed by the ME control unit. The mean pulsed heating current is approx. 400 mA in idle speed range. The current in the cold state is increased approximately by the factor 4. The sensor heater is switched off at coolant temperatures below approx. 20 °C and at high engine speeds as a protection for the sensor ceramic.

O2 sensor upstream of TWC (broadband oxygen sensor)
The O2 sensors upstream of TWC are heated continuously during engine operation, to guarantee their function.

Temperature control and temperature measurement (by means of an internal resistance measurement) are performed by the ME control unit by means of a special internal control electronics.

Voltage supply to the sensor heater takes place fused over the relay for circuit 87. Every sensor heater has its own short circuit-proof output stage with diagnosis switching to ground in the engine control unit.