Lexzo

Hey guys!! New to the forum but I am a Lexus lover just like the rest. I have a 1999 RX300 that is giving me two check engine light codes. One of them reads P1133 Air/Fuel Ratio Sensor Circuit Response Malfunction
(Bank 1 Sensor 1) and P1135 Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 1 Sensor 1). Just wondering what needs to be done to fix this and also how difficult it would be to do this.

Thanks,
Zo

Lexmex

Welcome to the Club. This particular sensor is behind the engine block, but what I recommend is pulling the battery cables off temporarily and see if the codes go away. If not, I would do a search on the forum as we have had quite a few thread on this code and suggestions as to how to change the sensor.

invadergsx

I just fixed my P1135 code. It's your primary o2 sensor. And from wasting a lot of money you take it from me not to buy an aftermarket o2 sensor. Buy an OEM Lexus one. I work for a car performance shop and can get them wholesale. I can get you one for $190. I think retail price was $235.

code58

The original equipment Denso's can be bought from an online Lexus dealer for $150. I would suggest you stay with original eq. Denso.