Hi,
I have a oxygen sensor socket but it is too large for the the oxygen sensor I have on my car. It seems to be an 18mm head. What is the best way of getting it off as there seems to be no room for a wrench to be able to move in that area.
Actually, I only tried to remove the back one. Can someone please tell me where the bank 1 upstream sensor is?

 

I use a 3/8" square drive 'flare-nut' wrench.
I keep two sets, one in SAE and the other METRIC.

 

Where is bank 1 sensor 2 located?
Thanks!

 

The OEM sensors are 17mm head. Bank 1 is the front 3 cylinders, sensor 2 is the one furthest from the engine, downstream of the catalyst in the downpipe.. It's on the backside of the downpipe, facing the block and is very difficult to get out. You'll probably not be able to see it except from underneath.

 

I am confused. So where would bank 2 sensor 2 be?
I understand that bank 2 is for the back 3 cylinders. So is bank 2 behind back 1? If so, then bank 2 is the furthest one from the engine. Sorry for not understanding this.

 

Hopefully this makes it clearer. Each bank has two sensors, one before the catalyst and one after.

 

Got it now. Thanks!

 

On the sensor connector the 4 wires on the sensor pigtail have the same wire color

On the other connector half 3 of the wires for each of the 4 sensors are the same as these wire continue to the ECU . the difference is the 4th wire which is the blue , red , green , or brown

The wires are very brittle and break as they a a uncommon galvanized , mine were broken ant wire sticking out the wire insulation

Bosch connector ready part # 13789 and the crush washer if missing can be obtained from a cheap 4 dollar autocraft plug # X

This crush washer if missing seams to have a difference on your sensors accurate sampling

Never forget to put antiseize only on the treads

I found some green corrosion in the rear connectors B! S2 and B2 S2

The critical wire for the sensors accurate performance is the 4th wire which is shielded and has a shield ground on the rear engine compartment firewall

 

I replaced one of my oxygen sensors today. It was very very easy to get to it from below with an 18mm wrench. It literally took minutes. From above, it was a pain to get the old plug off but eventually the plug came off. Overall, simple job done in less than 20 minutes.

 

In the interests of accurate information being conveyed, I might just point out that the spanner size for the O2 sensor is 17mm as advised by Jagboi64.
It is not 18mm, the use of which may provide a path to a further problem, a rounded off head.
The O2 sensors fitted to our Jaguars are in the minority at M12 thread & 17mm head. The majority today are M18 thread with 22mm head.

John Herbert
(1996 XJR)