Well its been over a year now and still cant figure out this code. I have an 01 xjr ive replaced transmission twice,replaced tcm and abs module but still get this code. Car will run fantastic one day then the next i get the trans fault have to pull over turn car off and back on and all is fine. Thing is if i start car and get on highway i can drive 500 miles no problem but if i have to slow down or stop then i get the fault. Any help or suggestions would be greatly appreciated.

 

what is the code ? it might help some one narrow it down for you .

 

P0730 incorrect gear ratio

 

Sorry to hear about replacing the tranny twice, the next place to check would be your rear abs reluctor rings (tone rings) for being gunked up or damaged. They are the link in the can bus system along with rear abs sensors that reads half shaft speed in relation to N2 and N3 input trans speed sensor at the conductor plate. That info is used completing whatever canbus algorithms are involved along with the ecm/tcm/abs/and shift lever assembly in calculating that correct rear gear ratios are present. Long story short, if rear tone ring readings are skewed by a damaged or gunked up ring you can potentially get inaccurate readings and get the PO730 code you are getting. While you are down there you should check for wheel bearing, half shaft, and differential bearing play as they can effect tone ring readings as well (anything potentially effecting position of ring to sensor placement). All easy stuff to check compared to swapping another tranny.

 

Thank you i will definitely check them.

 

I think the speed sensor on the electrical conductor board went bad and needs to be replaced. It is a common problem. I found my replacement on amazon.com.

Also, see my response here:https://www.jaguarforums.com/forum/x...p-home-161395/