lexlude

I have a 98 es300 and I get code p0171 off and on. The code comes and goes away by itself. I was thinking about switching around the two a/f ratio sensor. I tried cleaning the maf, I tried another used maf and then I also tried a new aftermarket maf and I still get the p0171 code intermittently.
Here is a snapshot

DRACO A5OG

No they are not, one is in front, easy peasy next to the exhaust manifold, bank 2 sensor 2

The more difficult one is the bank 1 sensor 1, you guessed it, it is in the back of the engine next to the firewall. Joy. it can be done but just a PITA

Remove the Sensors and if full of crud, burn it off with a torch. Test again with a torch and a DVM to see f moving the flame over you get 1 volt, if so then it will still be good after cleaning. If not, time to replace. Do not drop it or you will break the internals.

PFB

I think the sensors themselves are the same, but the cable length may be different

Check online to see if they have different Part numbers

lexlude

Ok I will check the cable length and also check to see if it need to be clean

artbuc

Wrong. B1S1 and B2S1 are the same except for harness length. The "easy peasy" in the front is B2S1. B2S2 is the downstream oxygen sensor. Is your car Calif emissions? If yes, your upstream sensors (S1) are the much more expensive A/F wide band sensors.

DRACO A5OG

I stand corrected.

lexlude

The California standard slip my mind. Couple years ago a friend of mine bought a used 97 camry. Check engine light came on couple months later for o2 sensor. I went to replace it and notice that the previous owner recently changed it.
Year later same code. I went to buy another and the parts guy asked as usual if it was California or federal emission. I usually say federal since I live in NY. This time I went to check under the hood and it said California emission. I bought the correct o2 sensor and never got the code again.
Since I live in NY I assume my es300 is federal emission. I will have to check under the hood tomorrow

artbuc

Where you live or where you bought th car has nothing to do with its emissions. I bought my 99 Avalon brand new in Delaware and it was Calif emissions. I believe emissions is based on the state which imported the car.

lexlude

Well I was thinking vehicle sold in California have to meet California strict emission standard. Those vehicle found its way all over the country somehow. I checked my es300 and it's. California emissions too. I change 02 sensor couple years ago and right now I don't know if I put the right one in

artbuc

Yes, of course a car purchased and registered in Calif must meet Calif specs. I was talking about cars purchased in other states which may or may not have been built to meet Calif specs.

DJPsystems

This might sound strange but my 97 ES300 that was sold brand new in CA uses federal spec 02 sensors. I found out the hard way when I ordered CA spec 02 sensors (Denso 234-9007 and 234-9009) and the connector did not fit, it was different. The proper sensor is Denso 234-4622 for bank 1 and 2.