RX300 year 2000. P1135 fault code

PUKU · September 11

RX300 year 2000. This has always been a reliable car for the past 15 years, except for the constant error codes, none of which has ever affected the running or the efficiency of the vehicle.

However, an issue that has been going on for months, mainly because it has not affected the car in any way is fault code P1135 Air-Fuel heater sensor. As this is a petrol car I assume this is an anomaly of over sensitive and complicated electronics of modern cars! however MOT due soon so I will need an answer for the MOT chap. Tried Lexus; and they don't know!!! Any pointers would be welcomed - I cant find the offending part even in the Lexus OEM workshop manuals or where this sensor is EXACTLY!

Any help or pointers would be very much appreciated; thank you for your time reading this.

ColinBarber · September 11

2 hours ago, PUKU said:

Any help or pointers would be very much appreciated; thank you for your time reading this.

P1135 is Bank 1 Sensor 1 Air/Fuel ratio sensor (Wideband O2 sensor) heater failure. The heating element on the sensor has gone open-circuit and the sensor will need to be replaced. It's a very common fault on any vehicle with a catalytic converter.

Being bank 1, it is at the back of the engine on the exhaust manifold so you would need to access it from underneath. Bank 2 is more accessible.

A genuine Denso sensor from Lexus is very expensive (part code 89467-48011). I would only recommend using a Denso sensor as the vehicle can be fussy with 'compatible' sensors, but you can use their aftermarket option, e.g.:

https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0500

PUKU · September 12

Thank you Colin, I have not found it yet but hopefully will have more time in a day or so. I am persuing the sensor purchase at this time.

ColinBarber · September 12

51 minutes ago, PUKU said:

Thank you Colin, I have not found it yet but hopefully will have more time in a day or so. I am persuing the sensor purchase at this time.

Here's a pic: