Lambda light back on after sensor replacement

[Yog Sothoth]

I had my '97 V70R down the garage for the lambda light on. The codes showed the rear O2 sensor was faulty, so they replaced it with a new one. All seemed OK, light was gone, but now just a few days and less than 10 miles later, the light is back on.
I did see something on here about removing a fuse or disconnecting thge battery to reset the system, and maybe it needs that after the sensor swap. Just seems odd it was OK for a short while.

[Clan]

Originally Posted by Yog Sothoth

I had my '97 V70R down the garage for the lambda light on. The codes showed the rear O2 sensor was faulty, so they replaced it with a new one. All seemed OK, light was gone, but now just a few days and less than 10 miles later, the light is back on.
I did see something on here about removing a fuse or disconnecting thge battery to reset the system, and maybe it needs that after the sensor swap. Just seems odd it was OK for a short while.

Is it the correct volvo one ? The rear sensor is very different to the front one .

[Yog Sothoth]

Originally Posted by Clan

Is it the correct volvo one ? The rear sensor is very different to the front one .

It was a universal one, not an actual Volvo part, but the dealer checked it would fit my car.
The garage said it cleared the fault code and it's done something because the idle is smoother (it was very variable before).

[volvo again]

You would probably be better off getting a better O2 sensor, cheapy ones often show a fault code in my experience.
Bosch, Denso are usually okay, have a look on PFS for some.

[brickman]

I think Denso are what was fitted new on these?

Lamda sensors are very sensitive. Chances are it worked for a few days as ECU had the long term trims all the way out, then as you've driven it with a functional (but wrong) sensor, its brought them back down to earth and sensor is throwing the code as its not quite the right one.

Its like with MAF sensors, buy cheap/fake/wrong/seconds, and you'll be buying several unfortunately. Garage might have had luck in the past with generics fitted to Kia's and vauxhalls, but rarely generics work on volvo's etc.