Where to fit lambda sensors for easy access

Can somebody tell me the best place in the new stainless exhaust down pipes I have to fit the lambda sensors? The body is CKD currently for repair/ repaint. I have to drill out the pipes, and weld in stainless bosses to accommodate the sensors? This is an XJS cabriolet uk spec.Build date 24/4/1987


Here are pics from my 89, but the best answers is to temporarily fit the pipes and mark accordingly. There is not much room for error.


Advice on someone who just did this and messed up (me), WAIT until the downpipes are installed, then take it to an exhaust place who can do it up on a lift in exactly the best place possible. It’s not just placement, but angle too.

There is not much room for error, as I found out. Ended up capping the holes and will take it in for 2nd try. Car runs fine with no O2 sensors, and just hanging there (I tied them up a bit).

Alternative is extend your O2 sensor wires and just go ahead and have the holes done near the end of the downpipes.

Hi Bob
Thanks very much for the pics. And yes you’re right better to decide when engine is back in situ.

Hi Greg
Thanks for your very sound advice. You’ve just confirmed my feelings on this! It’s been a very long time since I was under an XJS. I’m not going to try to guess the location of the lambda bosses.

Car is at exhaust shop right now. I had chosen the right spot, I just chose the wrong angle.
Definitely wait!

My solution is either buy new downpipes and fit again, or cap holes, weld new ones a bit lower, and splice O2 sensor wires a bit longer so there’s no tension.

They fit them lower, plenty of wire slack. Will post photos tomorrow.

Hi Greg
I’ve got new stainless down pipes. I’ll wait until the engine is back in the car. Then appraise the best position for them. Thanks again for your advice.