There should probably be a flow chart on solving this but this was my experience. After 1 year of running an lower temp t stat nos from an older diesel bmw-plug and play except for the electrical control wiring I started getting P 0128 codes tedfollowed by 131 and 134 codes iirc. So coming up to temp too slowly and then rich codes. Replaced temp sensor in lower rad hose, no help. Finally did the transcooler t stat as has been documented and the temp sensor (I believe it is called the oil/water sensor parked near the tstat.) I had removed the air inlet pipe to throttle body in the process. After reassembly I got the 1172 and 1175 codes. Retightened the clamps on the air inlet (I had wiped the rubber seals with a touch of the dow Corning silicone grease) and now after several drives the code reader finally went green. Of interest is that the evap code was the last blinking icon on the reader before it went green. Also I was getting trans overheat messages on start up or shortly thereafter but have not found the hard cause. I cleaned the contacts on the trans controller connectors had perfection, then a repeat of bongs, and then the last 20 starts, perfection again. The mechanic who has done the tranny twice went thru it with his reader and reset it (always that bit of mysticism) so will see what happens.