O2 sensor heater dead?

[jtjerry]

think I can have dead O2 heater in oxy sensor...
When engine is hot (1G T 1990) on idle (as I look at logger) O2 stay standing still at 0 volts. As I start driving it start making fine waves form 0.1 to 0.9. But when car is standing and idle there is no change in O2 voltage and logger always show 0.02v.
Is that symptom dead O2 heater or that is normal ?
thanks
Jerry

 

[pneumo]

Yes, that's a sign of a dead O2 heater circuit. It could be a problem with the O2 sensor, or it could be a problem with the wiring circuit that supplies power to the heater.

 

[jtjerry]

Today I buy and mount new o2 sensor.
All is as before: at idle there is no change in sensor readings. Always logger show 0.01v at idle.
There is 12v for heater, ground for heater, and all wires are ok.
Maybe that sensor work with OEM restrictive exhaust systems with cats and that all small funny pipes.
I have 3 in exhaust without cats. Maybe gases flow too fast to maintain enough temp on sensor at idle.
After all: all 3 sensors I changed (stock, used one and today new) works same way.
Can someone with big exhaust and data logger check that PERSONALLY?
Looks as all effort and money I spend at that sensor was wasted and that info (sensor work at hot idle) is...
Jerry

 

[pneumo]

I have a big exhaust ( full 3" with a ported EVO III O2 housing), and my O2 sensor works the same as normal.

What are the low fuel trims? Maybe the trim is maxed out and the ECU can't add enough fuel to bring the O2 reading up.

How old are the capacitors in the ECU?

 

[jtjerry]

thanks for info
tomorrow I will add some fuel at idle (have maft). maybe it is simple too lean at idle. capacitors have 14 years.

 

[1LE]

Hmmm, I have a problem very nearly like that and I reached the same conclusion. I have a new O2 sensor on order to try.

Mine works fine when the car is under load or at really high idle (>2k rpms). It will not drop to a normal idle after a start until the car is driven a little (even if coolant/oil temps are up). It will also work fine at idle if I'm just creeping around (25mph). If I drive faster than that and stop, it will hang at .8x for a few seconds, then drop to 0 for a couple seconds, then gradually count up to .05, THEN start cycling. Kinda like it's getting too cool from the airflow and having to heat up again.

Started VERY suddenly. One day it was fine, the next, this! I'm used to feeding the car a new O2 sensor every 1-1.5 years, but this is the first time I've seen this behaviour! Usually it fails by "sticking" while cruising.