Oxygen sensors

[Gingiebabe]

Just wanted to know if anyone knows where to get the pre cat sensor and the post cat sensor as can't seem to find these as I dint know the numbers of the sensors and they all seem to ask what cat it is ,I have a N reg 850 estate,thank you.

[Niles]

is your car a T5? N reg 850 will only have a pre cat sensor. The later V70's etc had pre and post. your car 100% will only have the front. I have a very good condition pre sensor spare if you need one. Only covered appx 25k miles. Perfect working order.

[nobananas]

As Niles said, you should only have a pre-cat Lambda on an 850. I bought a Bosch one for mine from Euro car parts a while back.

[Gingiebabe]

Sorry to say but it has the two sensors and me being stupid and inexperienced , i don't know if it's a t5 ,how can I tell ,need help bigtime,thanks for your replies guys .

[LiamT4]

Sorry to say but it has the two sensors and me being stupid and inexperienced , i don't know if it's a t5 ,how can I tell ,need help bigtime,thanks for your replies guys .

A t5 will be a 2.3 with a turbo, if you check the inside of the petrol cap it should say.

[Gingiebabe]

Then it's not a t5 ,as you can tell very new at this (can't even tell what my own car is)lol ,def has 2sensors though ,HELP.thank you for info though.

[LiamT4]

Then it's not a t5 ,as you can tell very new at this (can't even tell what my own car is)lol ,def has 2sensors though ,HELP.thank you for info though.

Has a garage told you that you need these 2 sensors replacing?

[Gingiebabe]

Yes they are both faulty but the post cat is stuck in an open position,

[Gingiebabe]

Sorry yes garage has told me so

[LiamT4]

Yes they are both faulty but the post cat is stuck in an open position,

Hmm, thats sounds strange to me, all the sensor after the cat does is measure the gases coming from the cat to make sure its working and the emissions are within a certain range.
Not quite sure how it could be "stuck in an open position"?

If you have an independent volvo specialist around they may be able to help, most independent places are pretty cheap to.

[nobananas]

Yes they are both faulty but the post cat is stuck in an open position,

I hate to say it but it sounds as if the garage doesn't know which one is at fault so they are changing both. At 80 - 100 quid a throw for a decent one that's a lot of money. As liam says the post cat sensor just operates as a check on the emissions to ensure that the cat is working correctly, it doesn't actually affect the running of the vehicle but will throw a MIL and catalytic converter efficiency code. It's possible that if the pre-cat sensor has failed it has left the system in 'open loop' which may be what the garage means (open loop is when the ecu doesn't use the Lambda for fuel metering but other sensors, the vehicle is in open loop when cold and also when under part or hard throttle, it drops into closed loop ie using the Lambda sensor for fuel ratio metering when at idle or constant rpm when the sensor is hot). Often a failing pre-cat lambda won't throw a MIL (unless it becomes completely un-reactive or the heater circuit is dead) but if it has failed in such a way as to cause over-fueling then the cat won't cope and the post-cat sensor will pick it up. The easiest way to confirm if the pre-cat lambda and the cat are okay is to have an MOT type emissions test done, this will give a good indication of what's at fault.