RX300 Lover

Possibly yes. But the sensors 12 yr old now so I'm betting it's the sensor. I'll test the old sensor when I get the front seat out if it's ok then it will confirm CAT in which case I'll take them off and clean them out.

OK after some research I have found that UK Denso part number (for US DENSO 234-4215) is DOX-0227 which corresponds to: Toyota OEM # 8946519595 (which is also the same as) Lexus OEM # 8946549075 Hope this helps someone save some money. P.S I am waiting for a sensor to be delivered will update when installed.

Does anybody know the UK Denso part number or OE number for DENSO 234-4215 sensor as I contacted Sparkplugs.co.uk and got this response:

Thank you Jason. Just for peoples reference the sensor at Bank 1 Sensor 2(DENSO 234-4215) should read 11 - 16 Ohms resistance (cold/20C). I'm gonna get my drivers seat out and test the Ohm measurment of my sensor as I've been getting CAT fault codes(P0420) come up and I reckon this sensor is on the way out and causing it. Will post results as and when.

If memory serves me correctly I disconnected the negative on the battery and cleaned the MAF sensor then all was fine. I used a proper MAF cleaner the Liqui Moly Mass Air Flow Sensor Cleaner one but judging from the smell its just isopropyl/rubbing alcohol anyway so you may as well just use that as it'll be cheaper. Oh by the way does anybody know what the sparkplugs.co.uk product number/code is for the AF sensor at Bank 1 Sensor 2 as it is NOT the same as the other two?

Bit of a long time to update this but just to confirm these sensors were fine and my car is running perfect.

Update: I drove car for about 10 miles and CEL came on again this time with codes P0174(bank 2) and P0171(bank1) both of these are "Sytem too lean" errors.

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? Or maybe it IS the DOX-0243 sensors but they(the new ones) are not registering fault codes for me and I checked their resistance with a multimeter and they gave the correct reading of 0.8 ohms so I am 90% sure that these Denso DOX-0243 sensors are ok(i hope).

Ok, I have replaced both sensors with Denso DOX-0243 sensors(£75 each inc vat) and the fault codes are gone and the car is driving fine. FYI both new DOX-0243 sensors resistance measured 0.8 ohms so it would seem DOX-0243's are fine in RX300's.

Ok I've just taken my 2 sensors out which are: Bank 1, sensor 1: Under and behind the engine block(right bitch to get to) Bank 2, sensor 1: On the outlet manifold(easy to do) The resistance measurments(taken cold) were as follows: Bank 1, sensor 1: 0 ohms Bank 2, sensor 1: 16 K-ohms/16,000 ohms As I understand it the resistance must be in the range of 0.8 to 1.4 ohms otherwise computer will display the P1135 and/or P1155 codes so I take it my sensors are toast. I'm going to remove the glove box and check the voltages from the ECU too.

Hi, currently have same problem with P1135 and P1155 codes displaying on a 2001(Y) plate. check out here and you will find a link to download a technical manual. Pages SF-75 to SF-77 have information on the air-fuel sensors with relavent ohm/resistance measurements. I noticed this manual is for an 03 model so I am not 100% sure if the 2001 sensors will have the same measurments, if anyone could clarify this would be great. This pdf file shows how to check the ECM for correct voltages to the sensors which would be worth doing if you think your old sensor was fine to rule it out. Did you check the resistance of your old sensor BTW?