i have a 1999 dailmer v8 i have had since 2000 without any problems recently it has been telling me that i have restructed performance plus plus Yesterday it connected me into the limp home mode with ORANGE AND RED glowing on the dashboard.

 

You are going to need to read the codes from the OBDII system. That looks like the first move. Folks on here can help from there.

 

a freind attached his code reader to my car and the codes were Po237 / P1646

 

I could not find P0237 on the code list I have. What I found on P1646 is below.
It sounds like an oxygen sensor, upstream, A bank. It seems strange you would get
put in limp mode for this. (?)

P1646 ECM HO2S control malfunction – A bank, upstream
HO2S heater failure
HO2S sensing circuit short circuit to
ground or high voltage
HO2S sensing circuit open circuit
ECM failure

 

i have been inforemed that po237 is the knock sensor

 

Knock sensor is P0327... there does not appear to be a P0237 that applies to your Jag - check with your friend again to make sure you have the numbers right.