I have a 04 Jaguar XJ8. I think it is misfiring because it jerk. The mechanic says it has bad oxygen sensors. Upstream and down I think he said. 143k miles.
1. Would oxygen sensors cause it to misfire or jerk.
2. I'm thinking It could be the catalytic converter.

Any thoughts. I haven't checked the codes so far.

 

Start with the codes. Do not guess / do not ask people to guess.

 

If it's a misfire, you will likely see an 'Engine Malfunction' amber light on the dashboard, and the symbol for that resembles something like an anvil. It could also be followed by a 'Restricted Performance' message on the dashboard as well.

You will need to pick up a code reader to ascertain exactly what the problem is, and the one that I would recommend is a Foxwell NT510 which you can commonly find on eBay.

In my case, I had a misfire in my 2005 Jaguar XJ8L earlier this year which turned out to be a defective ignition coil for the No. 3 cylinder.

 

Thanks for the help. I think you guys are right, I need to start with reading the codes first.