volvo s80 2.4 bias on o2 sensor

Hi everyone.

Anybody know if volvo use bias voltage on their o2 signal curcuit? I have 4 volts on b1s1 signal wire.

Also dtc on the sensor for signal fault.

This is a 2000 model if I remember correct.

The heater curcuit is ok drawing about 5 amps in total for both sensors. (If that is normal)

I can't find anything about it. Did you figure it out?

We have ordered a new one. 545 $.

Do you know what the normal amp reading of a heater should be?

I tried to do some research on this, couldn't find much Lots of talk about resetting adaptives after a sensor replacement, but little else.

A week ago I would have said no way, but then we had this thread about a 1V bias on a Toyota O2. Weird :blink:

Do you know what the normal amp reading of a heater should be?

If it's a good ol' zirconia O2, then I'd expect anywhere from 500mA to 1A. Five amps for two sensors seems a bit high to me... Knowing specified heater resistance would help give us a better idea of what these are supposed to be drawing.

I will measure the new one before I install it. It has to be bias voltage. When I measured the downstream it was steady at 0,8 volts. Pulled a vacuumline and it responded like it should.

Inge Jeppesen wrote: I will measure the new one before I install it. It has to be bias voltage. When I measured the downstream it was steady at 0,8 volts. Pulled a vacuumline and it responded like it should.

Works for me! Eager to hear the result on this one, my mind has been getting blown with these wacky O2 bias voltages recently...

Just for fun, I did some quick Ohms law math. *IF* both heaters are full fielded, and of the same resistance, then they'd be drawing 2.5A individually. That works out to an individual resistance of around 5 Ohms. Sounds low to me, but it's a Volvo, so who knows? :lol:

It is probably like a light bulb. Resistance/heat changing.

Before I discovered "SD" I did not know what bias was at all. When I watch his videos it's like : " ah now you are forgetting something Paul.... and bam... he sais exactly what I was thinking. Amazing.

So.......

Put new sensor in. Same 3.8 volt steady signal. After 5 starts and stops and the CEL is gone. :woohoo:

Heater resistance old sensor 2.5 ohms. New 1.5 ohms. Same model and make denso original volvo sensor.

Thinking this might be a broadband sensor?

Or is it a magical sensor?

Inge Jeppesen wrote: So.......

Put new sensor in. Same 3.8 volt steady signal. After 5 starts and stops and the CEL is gone. :woohoo:

Heater resistance old sensor 2.5 ohms. New 1.5 ohms. Same model and make denso original volvo sensor.

Thinking this might be a broadband sensor?

Or is it a magical sensor?

Wow :blink: This is an upstream sensor, right? I hadn't even thought about the possibility of a air fuel ratio sensor in a 2000 MY.

I'm happy that the car is happy But, strange... Just for my info, you had 3.8V on the O2 signal, but 0V on the O2 signal ground? Like you'd expect on a zirconia O2?

Yes it is the upstream.

3.8 volts on signal wire to engine ground.

I never measured signal ground wire since I got the 3.8 result.

Both upstream and downstream look the same. Except for the part number.

This is a strange case. Hope the CEL stays of...