I just bought a Lexus IS 250 with 110k on it . I got the check engine light code P0172 system too rich . I got a maf sensor and that didn’t work . So now I’m getting anew 02 sensor . .The brakes do go 3/4 to the floor , it stops but does not feel normal. I never felt a car with brakes like this but I was thinking it was brake pads or calipers until I got home and had 4 abs codes . C1223 ,(ABS MALFUNCTION) , C1249 (open circuit in stop light switch circuit), U0123 (LOST COMMUNICATION WITH YAW RATE SENSOR MODULE) U0124 (LOST COMMUNICATION WITH LATERAL ACCELERATION SENSOR MODULE) . All these lights stood on for a day untill I tighten the gas cap and they all went off . The check engine light comes on and off with P0172 system too rich code . I don’t know what’s going on. Any suggestions?

 

If you clear the P0172 code does it come back? Before you buy an O2 sensor I'd look at the vacuum hoses and do the "disconnect the negative battery cable for 30 minutes" procedure to reset the ECU.

Also, I'd use the search function as this question has been asked many times.

https://www.clublexus.com/forums/sea...rchid=23812308

 

You can try this to see if you are all gunked up with carbon at the intake valves. Try and floor your throttle on the highway, and see if there's a cloud of smoke, if there is, you have lots of carbon. Excessive carbon could be causing less air to go in while your MAF measured the air could be more, so system reports rich based on those o2 sensors in the exhaust. Report back if that's not the case.