1999 V70 xc 2.4l oxygen sensor locations?

[erikv11]

For example I do not have a second O2 sensor... There is no signs plugged hole or any indication for that, just an empty plug next to the front O2 plug (98 S70 GLT).

I sort of doubt it (only one O2) on a 98. Unless your car has a permanent CEL on? This sounds more like the SAS was removed but not plugged. On your 98, the second O2 is back under the car, see the link posted above.

@ kovi: I'm just thinking out loud here, no specific knowledge of P0030: on 93-98 models the front and rear O2 sensor are different parts; did you put in the correct one for the location? Also be sure to check the wiring and connectors, if you haven't already.

[Dirk1966]

You can maybe find out on this website if the car has one or two sensors

http://www.lambdasensor.co.uk/main/mindex.htm

Search on type of car and engine and see if it mentions a rear sensor
My 1998 NA V70 has only 1 sensor (B5252S) but my 1998 XC 70 AWD has two (B5254T)

[Atis]

@Erik: to be honest I still have doubts as well... I had three attempts to find that, but there is no wiring for that where it should be. I do not have a SAS system (european model).
Maybe the fcp video in youtube about O2 sensor replacement can help kovi to locate the diagnostic sensor.

[kovi]

what is the SAS system? that's a new one for me.

[erikv11]

... (european model) ...

Oh, that could explain it. Pretty good support for one-O2 setups from European posters here ...

The only thing the rear O2 does is check if the cat is working, that job is strictly emissions not operation so will vary based on location.

SAS is "Secondary Air System" i.e. it is a "smog pump" or "air pump" system that was put on some of the 96-98 cars. Again it is strictly by location, removing or disabling it (properly) does nothing to the rest of the vehicle operation except illuminate that pesky CEL, because the ECU doesn;t find the air pump when it looks for it. There are many threads here about how to delete SAS by tricking the ECU, you place a $1 diode across 2 pins/wires at the ECU. Or you can just turn off the whole system inside the ECU with tuning. You can actually turn off the rear O2 with tuning too, for that matter.

[kovi]

ah...air pumps.... thanks. never heard it called SAS before. this is just one big pain in the neck...

[kovi]

ok. I finally was able to get under here again... as compared to the pics of the 850? no second sensor...no cover plate either. so, here's my basic stats... 1999 V70 xc AWD. 2.4L turbo. I did replace the O2 sensor on the front of the converter already for a code of P0133. now, I have a code of P0030 (another O2 sensor code) after double checking the same area that the plug is for the front sensor... I DO NOT even see another plug for another sensor...thoughts? help? comments? the only other thing I can think of is maybe I got a bad brand new sensor?

[erikv11]

I know this doesn't exactly answer your questions and I don't drive a 99+ so I will try to keep from mucking up your thread but this is also relevant: what was the part number on the sensor you put in, was it a rear sensor or a front sensor? What brand?

A pic of the one you replaced might be useful here.

People have indeed posted occasionally about bad sensors out of the box, for what it is worth.

[kovi]

OK! I was finally able to get her back up in the air and do more looking. this has to be the dumbest setup I've seen..... I DID find two O2 sensors total now.... BOTH are before the cat..... per se. the upstream one is in the pipe, behind the turbo and above the flex joint. the SECOND one is right at the inlet of the Cat. maybe because it's AWD? maybe because it's a 99 (and that seems to be the transition year) maybe...????? I dunno but, I wanted to make sure this thread can help someone that may run into the same issue. good luck to all and thanks to all for the help!!!!

[erikv11]

On my XC70 the second in the front of the cat itself.
See the picture number two on this page

https://www.matthewsvolvosite.com/forums ... p?p=105215

ok.... if the one at the front of the cat is the second one....then ...where is the first? lol

More up front, like in (or almost in) the engine bay ... look at the downpipe with the hood open.

So did you get the correct part, for the sensor you did replace? If not, that might explain the codes.