Jun_he

Yes. It is the dead battery caused the hesitance and won't start at all. I have to jump it to get to Autozone to replace it with duralast. Thanks for all.

Simply the "mobil 1" sold in Samsclub. Don't remember what it says on the box: FullSync or SyncTech or something like that. I put "FullSynth" there simply to differentiate from hybrid type. Search "mobil 1" on Samsclub.com. You will get it. Here is the link http://search.samsclub.com/eclub/search.go...ch&logged_in=No Another thing I found in Walmart yesterday is that they charge only $32 for oil change with this exactly same "mobil 1" synthetic oil. Of course their filter is no good and I can't trust their people doing the job there. Still it is very tempting to let them do it.....

thanks for all the responses. The battery is still the original one. Is it normal factory battery last this long or short ? My experience with Jap car is that their factory batteries last barely over the warranty time. Doesn't matter if it is 30k or 50k ? Now at 59k. It seems to be just right.

I changed regular oil to Mobil 1 FullSync 10W30 yesterday. I found engine starts hesitantly as if the battery needs to be replaced. My 2001 ES300 has 59K. This is the first time I am doing oil change myself and chaning oil to synthetic after following many good advice here. The change is relatively smooth and almost no drip to the ground. Do any of you know why so ?

The B2S1 is longer than B1S1. Looks like I have to borrow some wire from the bad part and connect it to the good part. Too late to do this tonight. Eventually I have to replace the front one anyway and it WILL be a lot easier. I am going to beat myself now without checking resistence to confirm bad sensor before trusting the website. I noticed the inconsistency of the meaning of P1155 at very beginning (See my first or second post on this topic). But I trusted SKperformance's code list and troublecode.net too much. But looking at the better side, I replaced the difficult one without introducing more trouble code and now I am still going to be one of DIY guy converting from the full dealer $$$ guy. By the way, where did you get your repair manual. My Haynes book doesn't have P1xxx code at all.

I checke on another lexus forum and found 2002 ES300 has P1155 listed as Bank 2 Sensor 1 not B1S1 as I originally though. Is it different for 2001 and 2002 ES300, where is the reliable description of P1155 http://www.clublexus.com/index.php/article/view/2148/1/368/

I replaced B1S1 sensor Toyota Denso part# 89467-41030, which is exactly the same as the original one that is replaced. Engine check light and trac off light are still on. I cleared the code via method of disconnecting battery terminal method and/or autozone OBD2 code reader. After a minute I start the engine, the lights went back on and code reader stilll shows P1155. For OBD2 reader, I was able to clearly see the code is erased and 1 minute after I started my engine, it is back on. I double-checked on connection and part itself and everything is fine. When I re-connect the connector, I heard the click that means it was in place correctly, I looked at sensor socket they were exactly the same as the other one in front. Now I am lost. Where else I should look at? Can anyone help me here ??

Thanks for the confirmation. I checked again with another scanner and got same P1155 code. So I ordered the part from what Mike pointed out earlier. I will let everyone know how it works after I get it replaced.

steviej, Thanks for your most valuable input. Because I only get one code P1155 from autozone's OBD-II scanner, I wonder if that will be good enough to change out AF sensor ? So I tried to check out the resistence to determine if it is bad. B2S1 can be easily seen. But the B1S1's connector is reachable only from the top not bottom. It was dark so I have to check it today. The interesting part about these sensors are THERE IS NO MANUFACTURER LABEL on top of them. At least I couldn't find any under my flashlight last night. Normally you would expect any genuine Lexus/toyota part will have some Band name/ part# etc on it. But these sensors don't. Is it normal at all ? If Lexus tried to use subpar OEM part on this sensor, shouldn't it be their issue ?

Thank you very much on the pointer. I called dealer, since I bought it on Feb. 2001. So both mileage and years are out of warranty, they said it is completely out of warranty. They can't do much about it. I checked both sites. They don't seem to make difference between O2 sensor nad AF ratio sensor. This makes me worr a bit. In fact, when Lexus dealer quoted me O2 sensor at $170 this morning and changed to $270 later. This makes me think a lot of people don't know the difference between the two. The second site indeed has 20% restocking charge. I don't think I will need to restock it. But I got burnt before... I will continue to search.. One technical detail as to use jack & jack stand. I haven't used them for past 4 years since I got this new vehicle. Both are 2 tons. They worked for my civic. Will they work for my lexus and Odyssey? The jack is not floor jack but hydraulic. Do you think I would get enough height to work under on the 2ton jack stand ? Should I consider to buy a new floor jack as well ? Particularly after I was quoted from dealer $829 for 60k maintenance is outragous. If I am doing it now, I am doing it all for years to come.....

I checked with lexus and toyota dealer. The price is $270, $238+tax I searched on internet, seemes it will be about $220 for Denso part. Kinda afraid to get a part from internet and can't return it easily if it is a wrong one. Where can you get it for $180 ? As to warranty, ES300 is covered only 4 year/50k miles. I can call them to ask to make sure....

Thanks for the quick response. So it has to be bank 1 sensor 1 ie the AF ratio sensor at the back of the engine. It will be harder to replace for sure. Should I use Bosch universal part or Denso part ? Is it unusual for it to fail so early?? I did read some interesting exchange on a RX300 and its trouble to change so many things before he resolved issue. After reading these, make me feel a lot less trustful on these cars....

My 2001 ES300 has these two lights on. I went to AUTOZONE and did OBD-II and get only one code P1155. I checked on the internet. It seems to mean A/F ratio sensor heater circuit malfuntion (bank 1 sensor 1 ). But Some other place says it is (bank 2 sensor 1 ). I am confused. Which one is that ? Does Bank 1 mean at the back of the engine. My car has only 58k on it. Is it possible some other problems cause this code appear. Thanks for any input.