I have a question is it possible for a loose negative cable to trigger my 04 rx8 into limp mode. Possibly by arcing and causing a surge?

 

if you shot a surge through the ECU sure it is possible. Try resetting the ECU (key on, 20 brake pedal stomp).

 

K thanks. Car starts perfect no wierd idle at all just in limp mode...

 

Any codes?

 

Doin that friday if the reset doesn't work. I know it has had a bad front 02 for a month or so...

 

My car was recently in limp mode. It would intermittently switch between driving correctly and limping. Turned out to be the cat. Afterwards 'fixing' the cat, my car wasn't running properly. The the plugs were toast and one of the ignition coils was trashed, which isn't an uncommon occurrence when the cat goes bad. I'm saying this because the the bad cat manifested itself as an error code with the O2 sensor...

 

usually the other way around

 

details

 

So the only code it pulled up was Heated Circuit upstream 02... ? No misfires or anything. Would the Mop sensor throw a cel?