GF07.61-P-3025F O2 Sensor Heater, Function

GF07.61-P-3025F O2 Sensor Heater, Function
- 104 (except 104.98)
- 111
- 112 (except 112.96)
- 113 (except 113.989/99)
- 113.989 up to Model Year 08
- 119, 120, 137









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

The sensor heater is actuated by the engine control unit through ground. The performance of the sensor heater at operating temperature amounts to:
18 w on Engine 104, 111, 119, 120 and 112, 113 with ME2.0
12 w on Engine 166.
7 W on engine 137, 111EVO and 112, 113 with ME 2.8 as of 6/00.

The voltage for the sensor heater is supplied by the:
- Overvoltage protection relay model 124, 202 up to 7/96
- Relay module, model 170, model 210 up to 2/97
- Base module, model 129, 140
- Fuse and relay module, model 202 as of 8/96, model 210 as of 3/97, model 163 designation F1
- Electronics relay, model 166
- Right fuse and relay module (K40/7), model 215, 220
- Right fuse and relay module (K40/4), model 230
- Front SAM control unit with fuse and relay module Model 203, 209, 211

In the cold state, the current is increased approximately by a factor of 4. At coolant temperatures below approx. 20 degrees C and at high engine speeds the sensor heater is switched off.

Engine 112, 113
The sensor heaters for the left and right O2 sensors are connected in parallel in the ME-SFI control unit.

Engine 119
The sensor heaters for the left and right O2 sensors are connected in parallel.

Engine 120
The sensor heaters for the left and right O2 sensors are assigned to the respective engine control unit.

Engine 137
Each sensor heater has its own, short-circuit proof output stage in the engine control unit with diagnosis. As a protection for the ceramic, the sensor temperature upstream of TWC is limited to approx. 350 degrees C in the condensation phase after cold start. After this, the temperature is controlled to approx. 700 degrees C. The exhaust temperature is determined from various engine operating data for this purpose and the sensor heated accordingly.

Different values apply to the O2 sensor heaters downstream of TWC.