I haven't seen this on here so here it goes:
On P2 (except S80 below chassis # 51300), P1, and P3 models you can see if you have fault codes by holding the left stalk end button, the READ button, depressed and then turning the rear foglamp switch on and off. You have to be sitting still, will not work moving.
The message display will start with ABS and punching the READ button scrolls through the module list.
The possible results are: NO DTC SET
DTC SET
NOT READY.
Not ready means there are no DTC's but that module has not completed its diagnostic routine yet. Some modules require some road speed and other require some period of driving before the diagnostic checks complete.
No actual codes are displayed and codes can't be cleared via this function.