Got the P1135 code and I was able to remove the pre-cat sensor under the car. Lexux wants about $230 and I can get it online for about half that. The parts guy at Lexus suggested that I replace the other sensor (front of engine just off the exhaust manifold) at the same time because they usually fail at about the same time. He also said they are exactly the same sensor. I thought they were different. Any experience and thoughts on this??? I don't want to order the wrong parts but I think it does make sense to change them both.
2002 RX 157,000 miles

 

Anything can happen, but I changed the rear one about 2 years ago and the car's been running fine (except for my transmission problem) w/o changing the front one. I would just change the rear and see what happens. My 2 cents.

 

That is why they call them stealerships. I'm sure they have replaced many, many working A/F sensors with that line of BS.

Yes, they are the same part. They used to be different parts when they had different length wiring harnesses to match factory install. For some reason (I assume just to reduce parts inventory) Toyota went to one part.

 

One thing I've said about A/F sensors is that sometimes after you replace one, the other one may give funny readings trying to stay in check, but that doesn't necessarily mean you should just get 2 right at the start. Wait to see what happens. I probably would replace both just because I get a bit **** about exhaust stuff in general, but that's just me, but I don't recommend that to anyone else

 

In my other car '96 Toyota Camry, I was cheap and didn't want to replace the o2 sensors, so I added STP fuel system cleaner to every tank, after 5 tanks, I never saw that CEL pop back up, and the resistance on the o2 sensor were perfect. And that was 3 years ago. Just a thought...

 

Occasionally there is 'garbage' in the gas. I used to have the same issue in Mexico and would run cleaners to get those A/F sensors right. I used to use the STP product in my old 90 BMW 325ic, seemed to work just right for that vehicle back in the 90s.