uk_lexus

Well thanks for your help code58 I've now reset the fault codes P0171+P0174 and driven it 10 miles and the codes appear to be gone. :) I reckon the greased lightning fuel cleaner had blocked a valve or something similar. But for anybodys future information the Denso DOX-0243 air/fuel sensors do work on a mark 1 RX300. They cost me £75 each which is a big saving from dealer prices.

I've just done some double checking and just to clarify some terminology here air/fuel sensors are the pre-cat oxygen sensors and then there is the heated oxygen sensor(I think there is just one of these) which is post-cat. I checked the resistance of the DOX-0243 with an ohmmeter and it gave the correct reading of 0.8 ohms so it definitely is an air/fuel sensor. Apparantly the resistance of the "oxygen sensor"(bank 1, sensor 2) should be 11-16 ohms. Do you know if the RX300 has 1 or 2 of these post-cat oxygen sensors BTW?

Correct me if I'm wrong but the air/fuel sensors ARE the O2/lambda sensors - they are one and the same thing I'm sure. From Toyota: Also from: http://www.densoaftermarket.com/oxygen-sensor.php

I saw this post on the UK site so decided to give the sensors a go. And yes they are the air fuel sensors both sensor 1 pre cat sensors(bank 1 + bank 2).

Hi Folks, The story so far on my 2001 RX300: Had codes P1135 and P1155 come up(air fuel sensors) so removed the sensors checked their resistance and they were both toast so replaced with Denso DOX-0243 sensors and codes were gone. Then I drove car for about 10 miles and CEL came on again this time with codes P0174(bank 2) and P0171(bank1). Now before I managed to get my own OBD-II scanner I thought it was a fuel problem as the car was missing so I put some Greased Lightning fuel system cleaner in it - would this be related? Any suggestions???