View Full Version : Help with fault code


318 ti
12-17-2002, 09:00 PM
:help

I just got a check engine light on my ti. The fault code reads "After Cat oxygen sensor heater." I can't find any reference to an oxygen sensor heater in the Bentley manual. Does anyone know what this is refering to?

Thanks

mjfeeney
12-18-2002, 10:58 AM
Oxygen sensors need to be warmed up to the proper temp before they start working. Until then, the car runs in a default mode which increases emissions. To minimize the time the car runs in this state, the O2 sensor has a built in heater. That's why there are 4 wires to the sensor. 2 for sensing, and 2 for heating.

318 ti
12-18-2002, 12:10 PM
Thanks for the help. I'll just get another sensor.