thanks for the insight.... the car went a whole month without an issue and now *poof* there it is again. just for the giggles of it.... I closed up all the doors, locked the car.... opened the car, put the key in and ...you guessed it...*poof again* started right up.

I have the same 1999 v70 xc as before (for any of you that remember) according to the dealer, it is one of the first cars with the immobilizer. can someone explain to me HOW it immobilizes the car? does it kill the fuel pump? the starter relay? or something else? Out of nowhere, I will get a crank w...

lol.... you and I both.... if you go to www.rockauto.com and punch in all my info.... you'll see the 6 or 7 different sensors they list.... you cannot even go my production date because so many of them overlap. you have to go by the connectors and ....maybe pray a little?

I did get the correct parts and all codes / lights are officially off for 24 hrs and about 50 miles so far...
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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 a...

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...

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

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

Thanks Atis and everyone else that's trying to help. for those curious, I am a machinery mechanic for a living but, have never worked on Volvos in my life. I'm working from ramps because I do not have a lift at home. I did replace the sensor at the front of the converter (as shown in the pics linked...

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