Have a 1999 rx with 198,000 on it. Have 3 codes:
P0125 INCOOLTEMP
P1135 AFOXYSEN
P1155 AFOXYSEN.

Question: is the P0125 mean that I should change the thermostat out even though it reads where it always has(right below dead center). Or do I need to change out both coolant sensors and the thermostat.

On the P1135 and the P1155, I don't think that the P0125 has anything to do with these two but they came on all at the same time. Have checked all the connections and even cleaned the MAF sensor. Guess if I need to change the bank #1-1 and bank #2-1 I should just change out the bank 1-2 also. Thanks in advance.

 

Ignore P0125, pop in a new Denso/OE A/F sensor in Bank 1 and it will be good to go. Replacing Bank 2 is optional, but not a bad idea. Bank 1 Sensor 2 should not need replaced at all.

 

This ^^^^^^^.