2006 V70 - Rear / Downstream Oxygen Sensor Removal

a3inverter · Post by **a3inverter** » 25 Jul 2021, 19:20

Been reading that the later P2 rear / downstream Oxygen sensor is a bit of a PITA to remove. I don't really want to drop my exhaust to do this - in fact, I may farm out the work to a local shop if that's the case as I have state inspection coming up and need to get rid of that particular code (I've had the code for about a week)

Any tricks? I've got the offset 7/8" o2 sensor socket that allows one to pass the wiring through, but tonight I came at it from the passenger side (based on some videos of the same job on early P2's) and found I couldn't get a good grip (nor could I see the sensor itself sticking out of the cat at about 2 o'clock).

All feedback is welcome!

Thanks!

Post by **GlennG2759** » 25 Jul 2021, 20:13

I have the same vehicle ‘06 V70. I heated up the O2 sensor bung and used this style O2 sensor wrench. Offset handle w/swivel slotted head, worked great. If your not in super rush I can mail to you. Glenn G.

a3inverter · Post by **a3inverter** » 26 Jul 2021, 06:06

Thanks Glenn - unfortunately this is a bit of a rush situation, but appreciate the offer. Looks like a very specific tool!

Post by **abscate** » 28 Jul 2021, 04:19

I miss my weekly run into Boston. Maybe those will start again soon

I’ve had lunch with the CTA crows foot OXS tool, too o a tight BMW sensor

Post by **chrism** » 29 Jul 2021, 03:57

On my 2003 V70 I was able to access the rear O2 sensor by just disconnecting the exhaust flange AFT of the cat and leaving the forward flex pipe connected. I only dropped the rear far enough down to get a wrench on the sensor and not bend the flex pipe any more than necessary. (Support the aft end with a Jack stand or cardboard box or whatever.)

a3inverter · Post by **a3inverter** » 29 Jul 2021, 07:39

Appreciate the replies. I had to get the car inspected (an annual joy here in the Commonwealth) and just had the shop do it. $50 labor and I supplied the part. Interestingly, 2006 is now exempt from emissions testing so it would have passed inspection with that code (P0037 if memory serves).anyway.

Post by **jonesg** » 30 Jul 2021, 02:47

yeh but it would have run like junk and soon ruin the cat.

EngineeringBloke · Post by **EngineeringBloke** » 18 Aug 2021, 11:10

I thought the rear O2 sensor was only used to detect if the cat was working. If the cat is bad, then the rear O2 sensor reads similarly to the front sensor. This throws a CEL warning that the cat is bad.

However, I have read that the rear O2 sensor is used in some other manner, too.

If I am mistaken, I'd like to know as I have only replaced my front O2 sensor and the rear one is 2006 original.

Post by **abscate** » 19 Aug 2021, 06:05

EngineeringBloke wrote: ↑18 Aug 2021, 11:10 I thought the rear O2 sensor was only used to detect if the cat was working. If the cat is bad, then the rear O2 sensor reads similarly to the front sensor. This throws a CEL warning that the cat is bad.

However, I have read that the rear O2 sensor is used in some other manner, too.

If I am mistaken, I'd like to know as I have only replaced my front O2 sensor and the rear one is 2006 original.

I believe that is correct with the P2

Front OXS feeds back for closed loop

Rear OXS just monitors cat for efficiency.

Jimmy will give me a face slap if that’s wrong