I have a 97 metro 1.0 3cyl. my obdll reader tells me my heater has failed on o2 sensor #1,does anybody know if #1 is on the exhuast manifold or at catylitic convertor? I put a ohm meter on the exhuast sensor and it read 6-8 ohms cold or even after the car ran for 20 minutes. any help would be greatly appreciated! thank's Dave Adams (my obd reader gave me a code of something like 3042 or 30140) I can't remember I'm at work and don't have the car here.

Well, the heater on the o2 sensor is just for when the engine first starts. It pre-heats the sensor so it doesn't take time to warm up. The sensor itself is probably fine, it's just not pre-heating properly. #1 is on the exhaust manifold.

geozuki where is the heater and how do i check it,fix it? If anybody knows I'm sure it's you! thanks,dave adams

it's built into the o2 sensor. To fix it you have to replace the whole unit.