1998 XC70 oxygen sensor mystery
 

Due to some loss of power when driving and reaching 120,000 miles, I planned to change the O2 sensor. I checked all of the major auto parts stores and located the part number of the front sensor, but now that I'm under the car I am baffled.

1. It seems I don't have a rear sensor, only one in the front which is actually located in the catalytic converter (towards the front of it). Shouldn't this car have a rear O2 sensor?
2. The sensor that I bought (Bosch 15097) is about 8-10" too short. It can't reach the connector.

Anyone know what this sensor really is, and why there isn't a second one?

Thanks!

There should be a second one located just above the center plate with 4 12MM head bolts.

yes this car should have 2 1 pre cat one post cat

Bosch # 15097 is your front O2 For turbo and non turbo
Bosch # 15063 is your rear for turbo models
Bosch # 15062 is for non turbo

I must have some strange setup, because I don't have a second one, and the first one may be the 15097 but the cables are way too short. The connector looks the same, but it just won't reach. Wonder why mine is different?

why are you changing it ? did you have high nos ?

Actually it was second on my list of things to change due to losing power periodically while accelerating. First on my list was the fuel filter. I changed that yesterday and I think it took care of the problem. It felt like the engine was being starved and there were no codes. After reading some other threads I also suspected a sporadically failing O2 sensor. I just replaced the MAF sensor about a month ago, which took care of another stalling problem that threw codes. I drove the car quite a bit yesterday afternoon and it ran great. I could really feel a difference in power, confirming that the engine was not getting what it needed.

Regarding the O2 sensor, I'm not going to change it now, but the mystery of the missing rear O2 sensor remains. And the long O2 sensor cables are still puzzling.

Does anyone else have a '98 XC with this configuration.

hello how are you
 

the O2 sensor is for fuel mixture if your nitrous oxide levels are high but todays fuels have so many additives in them sometimes it makes varnish in the lines which is caught in the filter and if you change to another brand the 2 can make the varnish harden on the element in your filter , did you blow through your filter to see if it was clogged ? if so , point proven . scott