Are there more than two O2 sensors on S70?

legger33 · Post by **legger33** » 30 Jan 2013, 11:11

Hey All,
The check engine light on my 1998 S70 has been on for over 4 years now and my mechanic (and I) have determined from the code that it is a faulty O2 sensor. I have replaced both the forward and rear sensors on two different occasions but the light comes back on. My mechanic thinks that it could be faulty wiring. I'm still getting good mileage (20+ city/27+ hiway) so I've just lived with it. Recently, though I talked with another mechanic that told me that there are actually FOUR O2 sensors - two forward/two rear. IS that true? if so, that would explain a lot. Otherwise, does anyone else have a clue what would cause the O2 sensors to code that they are not functioning?
Thanks and have a great day!
Steve

Post by **rmmagow** » 30 Jan 2013, 11:15

I'm interested to see what comes of this. I've been looking at new catalytic converters for my 98 V70 Turbo and a lot I've seen show three. I've not looked all that closely at my exhaust but my monitoring tool seems to see only 2.

jdmack · Post by **jdmack** » 30 Jan 2013, 11:38

There are only two sensors on the car. One before and one after the catalytic converter. I am no technician but If you could post the specific codes that are present I am sure someone on this board can help better diagnose this problem in detail and help get to the root cause.

Post by **boosted5cyl** » 30 Jan 2013, 11:47

There are two total. Period. The T6 has two banks with a total of four sensors, that might be what the second mechanic
You may find that vacuum or small exhaust leak is causing the codes. Post the specific code #'s if you can. Without them it's hard to help.

**Rant warning**
It still astonishes me how many "professionals" pull some codes and swap out sensors without looking at live data, freeze frames for doing any actual troubleshooting.

Post by **jblackburn** » 30 Jan 2013, 11:56

Recently, though I talked with another mechanic that told me that there are actually FOUR O2 sensors - two forward/two rear. IS that true? if so, that would explain a lot. Otherwise, does anyone else have a clue what would cause the O2 sensors to code that they are not functioning?

Go do this to that guy. He has no idea what he's talking about.

Also, what code are you getting? Most often, O2 sensor errors on these cars are related to vacuum or air leaks.

legger33 · Post by **legger33** » 07 Feb 2013, 16:13

Thanks everyone...and jblackburn, if I ever see this guy again, I'll find the nearest salmon and give him a good slap. Funny stuff! I don't have a code reader but the next time I get it, I'll post the codes. Thanks all!

And as Phil says in Groundhog Day - "Don't drive angry"

Post by **jblackburn** » 07 Feb 2013, 16:15

jblackburn, if I ever see this guy again, I'll find the nearest salmon and give him a good slap

Good man.