hi i drive 98 volvo v70 non turbo with 209k on the dash peeking under the hood this week i notice a small pinhole in the center of the check valve for the secondary air system the one at the back of the firewall with the purple line connected would that throw a p0133 code and or would that give me a vacuum leak for the same code

The P0133 can only be generated by the front O2 sensor. How old is the sensor? 100K miles is old age.

A vacuum leak for the SAS will generate its own code.
--
Keeping it running is better than buying new

i changed both front and rear 02 sensors when i had put on new cat and muffler but i had this code before i changed stuff i think i have a vacuum leak some where

Unless you buy gas in Mexico, your old cat should have been just fine. But, since you replaced the cat and the O2 sensors AND had a P0133 before and after replacement, I question which O2 sensor brand you bought. If you are in the rust belt, did you clean the contacts for the O2 sensors, above the transmission? Did you add the extra length plug with the front sensor?

A vacuum leak will cause a lean/rich code, not a P0133.
--
Keeping it running is better than buying new

yes i had code before i changed anything and i always use bosch oem 02 sensors did front and back at same time dealer plugs to expensive bosch next best thing and did not change 02 sensor adapter but will buy new front 02 sensor and 6in adapter and see what happens

Suggest just putting in the longer plug as Klaus suggested and see if that cures it. A vacuum leak will throw a different code because it definitely affects the mixture.
--
Will I buy another Volvo??? We'll see....

ok cool if i replace new front 02 sensor along with new adapter what else should i look for if that doesnt cures it my 98 volvo v70 non turbo is clean looking with a few dings i love this car

Please read the responses. All you may need is the cable:

https://www.fcpeuro.com/products/volvo-oxygen-sensor-cable-front-9202714

Just make sure you clean the contacts before you plug the cable in.
--
Keeping it running is better than buying new

thanks to everyone for there help ill let you know how i made out soon

hey guys still the same thing now i tested the o2 sensor side the 2 white wires are the heater i got continuity with a meter good now i want to test the pcm or ecu side of the o2 connector but not sure which one to test to the negative battery terminal to see if ecu is putting out 12v im wanna sat the brown wire on the ecu side to the negative battery terminal should give 12v im i on the right page

Is this the OE plug-n-play sensor you installed or did you use a "universal" unit?

https://www.stockwiseauto.com/bosch-15097-oxygen-sensor?Year=1998&Make=Volvo&Model=V70

i only use oe or oem parts i changed both sensors front and back with bosch 15097 and 15062 or 9202719 & 9202720 volvo part #

On my 2003 V70 there is a fuse that powers the O2 sensors - probably powering the Pre-Heat circuits in the sensors. Have you checked yours for a possible blown fuse?

no i havent will check 2morrow when i get out of work you wouldnt know the fuse number for a 98 volvo v70 nonturbo o2 sensor fuse

Sorry, I couldn’t ID a fuse number. Also, having never owned a P80 car, I don’t have a good wiring diagram either to try and trace how the sensor is powered. I’m thinking you should be able to attach a volt meter to the heater wires and see if it’s receiving power at start-up. As I recall my 2003 sends power to the sensor heater the moment you turn the ignition on - the engine doesn’t need to be running. Therefore when the sensor heater went bad I could get it to throw a fault code by simply turning the ignition on.

Are you 100% sure that Bosch is OE and not Denso? What does a dealer parts guy say?

no there bosch sensors for the vehicle from fcpeuro.com

now for the upstream 02 sensor harness the engine side of it from left to right the 4 colors are brown green/white stripe green/black stripe and green/orange stripe does that sound about right

The upstream sensor in my '99 non-turbo was Denso. The factory original said Denso as well as Volvo on it.