Replacing front Oxygen sensor 2001 C70 T5 Auto
 

Hi all,

In case it helps.

I am replacing the front Oxygen sensor on my 2001 C70 T5 Auto.
(Getting MIL Malfunction Indicator Light and Torque app with Bluetooth dongle shows code P0134).

Searching on https://fcpeuro.com/ they say I need Volvo Part 8627750.
I can confirm that from the old sensor while it is still in the car.
Looking at the cable I can see that it has five wires.
The old sensor needs a 22m spanner or special socket to remove it.
My old 22m sensor socket has a slot that is too small to slip over the shielding that is around the cable at the sensor end.
I don't want to destroy the old sensor quite yet, so I cannot cut it and use a standard 22mm socket.
So I have ordered a Hilka socket from Screwfix. I'll see if that works.

Meanwhile, I couldn't see how to undo the wiring to the sensor. Removing the pipe from the air box to the turbo made it much easier to see what is going on.
On mine, the connector block had already come away from its mounting bracket, and I can now see that I just have to lift the white clip back and then the cable will unplug.

New Bosch sensor has been ordered, and I will report back when the job is done.

Steve

Continuing with the removal of the front oxygen sensor on a 2001 C70 T5 ...

Access to the front sensor was very difficult.
If you loosen the cable ties that hold the heat shield sleeve, you can then slide it back away from the sensor, letting you slip your split sensor tool on.
I used the half inch drive Hilka fitting (see photos in previous post).
At best I could turn the sensor 1/20th of a turn, and move it back and forth.

To move it further either required more force or more space or both.

Access was greatly improved by removing two guard plates. Photo attached. I don't think these are found on V70s. Removal of those was easy.

I tried heating the downpipe with a butane/propane torch but I didn't feel that it was making a significant difference, and I felt that there was a good risk of burning or setting fire to something unintentionally. Maybe an oxy-acetylene torch would give a more localised heat and have more effect.

My 3/8 drive sensor removal socket wasn't deep enough to reach the hex on the sensor without cutting the sensor wire which I was hesitant to do because then there would be no turning back.

I bought another sensor tool, the shiny swivel split wrench, but there was so much play in the swivel knuckle that it didn't help me turn the sensor any further.
Photo attached.

Sprayed penetrating fluid and left overnight but that didn't seem to make any difference. Sensor points upwards so there is no hope that the fluid will run (up) into the threads.

When I did go ahead and cut the sensor wires I found that the 3/8 sensor split socket with a swivel head ratchet, or breaker bar, started to open up and was starting to round off the hex faces.

Next approach was to cut the sensor body so that I could get a 22mm socket straight onto it.
It wasn't a deep socket so I cut close to the hex head.
There was not enough space to get a hacksaw frame in there.
I used a Junior hacksaw but it was very slow going.
I then used an oscillating saw but the blades became blunt very quickly.
After a couple of hours I had only managed to cut 1/3 of the way through.

Eventually I used a small angle grinder with a cutting disk (and guard removed). I was very careful not to cut into other things that were nearby (for example power steering pipes). That made very quick work of it.

With the sensor body shortened I could get a 1/2 drive 22mm socket on, with a breaker bar or ratchet, working from near the bottom of the anti-roll bar drop link inside the left front wheel and removed the sensor. It was tight all the way out. Photos shows how messed up the threads on the sensor were. Threads in the hole seem mostly OK.

IPD sells a thread chaser, and indicates that the thread is M18X1.5
https://www.ipdusa.com/products/1004...ad-chaser-tool

I ordered one from Amazon
Sealey VS528 Oxygen Sensor Port Thread Chaser M18 x 1.5mm
for £9.12 delivered.
Of course, those are also available on ebay (as are various other brands and non brands).

I'll post back when I get the chaser and can continue what is turning out to be a tricky job.

Hope that helps someone.
Steve