What is the difference between P0133 and P1133? I believe my car has thrown both of these error codes because I've written them down, but I can't find any difference by Googling them.
The difference is regulatory not technical. P0133 is the SAE generic version. It satisfies the USEPA and CARB that this failure is covered under a code and conforms to regulated descriptive language. P1133 is the GM version that is used in the their diagnostic system. Both have the same failure criteria.