Jaguar xj8 4.0 v8 gearbox fault error

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Hi guys im a new to owning a Jaguar xj8 4.0 v8 1999 model 58k mileage. I normaly prefer the german cars v6 v8 etc so new to this tyoe of jaguar xj8 sovereign model although my father purchased one brand new back in 1999. Since iv have bought this car iv experienced many issues, mainly restricted performance issues. iv replaced 3 coil packs so far seems to have made the restricted performance error dissappear, so running super smooth bare in mind everything is orginal since 1999 nothings been changed other than a throttle body. I only use v power so the engine can run at its best, so i decided to do a resonator delete i had surge protection on the battery. Since i had did the res delete is come up with a gearbox fault code issue, in reverse its fine neutral fine park fine manual shifts fine, so i have diagnosed it today and has some codes
Po790 mode switch malfunction
Po763 shift solenoid c electrical
P1647 heated oxygen sensor control module bank 2 open/shorted
P1341 cam shaft postion sensor 2 circuit range performance.
I have tried a tcu ecu hard reset still the same i have plugged in few different types of obd scanners to see if i could earse the fault code but the gearbox fault error stays.
Not too sure on what exactly should i do first so i could save some moneys. I have it booked in this Friday to have a major service.
Any help any advice would be great.
Thank you

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did you go near the exhaust sensors or gearbox wiring ?

was it clear of codes before you started work ?

1 Like
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Hi
I was away from any sensors on the gearbox and exhaust , codes before were showing misfire coil pack b c etc iv changed them restricted performance went away then i decided to do a resonator delete.
I havent checked for any blown fuse or relay as i had protected the battery before i started wielding .
Thanks

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Resonator delete? Welding? What do you mean?

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Hi
On the xj8 models you have 2 cats 1 large resonator which is the same as a silencer, 2 silencer and 2 rear mufflers… After i cut it out i replaced it with 2 stainless steel pipes half a meter long. Wielded 1 side and clamped the other side on to the existing exhaust.