archangels

I bought my rx a day before easter sunday 30 miles after leaving the dealership cel light and vsc light came on, told the dealership about it said it was probably gas cap not on right i re capped gas cap still did not solve problem, i bought used and even called the manager but no return call, maybe they knew something was wrong thats why it sold so cheap on the market, luckily nothing major just maintenance, so i bought my own ob2 scanner(GOOD INVESTMENT) then got code reading P0171 and p0174 system running too lean, i brought today to my local mechanic and was surprised he only had a basic ob2 reader knowing he owns a business i thought he would have a live scan0b2 reader turns out the one i bought at preppyboys was a better 0b2, he said that it was probably do to the 3 02 sensors, i told him there are 2 a/f sensors and 1 02 sensors then we were debating he said that i knew nothing about engines and etc, he said were did i hear that from he said they don't know nothing but i told him other folks from this enthusiast lexus forum said there was 2 a/f and 1 02 sensors, then i called lexus and the lexus enthusiast said 2 a/f sensors and 1 02 sensors, so i knew for a fact to listen to this forum, i will follow the sticky lexmex recommended to save cost hopefully it just needs cleaning(too save on cost very pricey) if that don't do it then i guess i will buy 2 new a/f sensors and an 02 sensor but i wanted to ask is it possible to just take off 02 and a/f sensors and clean them if there dirty, or reusing them wouldn't make them good as good enough? the surprising thing is that when i bought the rx the said they did a 150 point inspection and it passed smog? so if it passed smog why would a/f and 02 be bad from day 1? thanks also today is the first day i used oil change with mobil 1 synthetic, car runs smoother and more quiet want my rx to run to its best for years to come, also my mechanic said change every 40,000 miles automatic tranny oil with filter? how many miles do you average change tranny oil? i got a printout
said tranny service was done at 60,000 mile service at lexus so wondering how many miles til next tranny service, also i slapped some dura lube has anyone tried this? was thinking sick 50 or duralube and bought duralube motor sounds quieter on start ups acceleration smoother. thanks also having a/f and 02 sensors can they save fuel and better overall acceleration and etc if changed? thanks

Lexmex

If you go through the the trouble of taking off the O2 sensors and A/F sensors (especially A/F sensors), just go ahead and replace them.

Vehicles used to pass in Mexico City with bad A/F sensors and O2 sensors all the time, in part because most vehicles have a default condition to prevent further damage. In addition, it is possible to reset the sensors, and if you are lucky, sneak in and pass smog before the lights come on again.

For tranny oil I recommend going no more than 15K. Would avoid slick50 or duralube. Replacement of A/F sensors can improve performance depending on their condition, but O2 sensor is not in the performance equation, strictly emissions.

archangels

lexmex glad you responded... ok i will try that proceedure sticky on gas mileage first, if lights go on still i will go ahead and change a/f sensors and 02 sensors, either way if i cleaned first the procedures you mentioned in sticky its better cleaned then leaving it. thanks for your help but 1 quick question lexmex if i did not change a/f or 02 sensor in a long while can it in due time cause bigger problems if not changed on time or soon leading to major problems to engine and etc? thanks im at 70,000 something miles, previous owner had tranny service done at 60,000 miles s i guess 75,000 miles i will do another tranny oil change... beter for tranny anyways to preserve it... also is the tranny filter expensive? i talked to my mechanic he said all i need is the tranny oil (are these expensive?) and gasket he told me the tranny filter he will just clean the screen? does that work or is it best to just replace the tranny filter so i was wondering if it was expensivefilter or hard to change as my mechanic only wants to clean the screen filter? isn't it best to change the tranny filter instead of clean? or cleaning is ok? i don't know what a tranny filter looks like so im confused, also every 15,000 miles change tranny filter always or just drain and fill thanks buddy

thomas1

The normal stock tranny filter is no more than a screen, They cost about $43 and can be replaced (as I did) but a waste of money. They can be cleaned and reinstalled. It is very important to never let the fluid turn color or smell burnt in this vehicle, It will preclude a failure of the transmission. Do drain and fills at 15k miles and if cleaning it up the first time do three of them in a short period of time. Your fluid will look prestine then. By the way many of the aftermarket filters are not screened and actually have filtering medium. Lex Mex and I are curious about the performance of the trannies with and without the filter medium or the use of the original equipment filter screen. Make sure to use Toyota Type IV fluid unless you switch to Amsoil. There are not any alternatives. Mobil 1 synthetic is not compatable according to Mobil 1. They do have a non synthetic 3309 fluid that is complatable.

Lexmex

thomas1,

I remember somebody in Mexico with two Toyota Harriers (diplomats) many years ago who tossed in Mobil 1 ATF, but never heard the long term story on that. Found it strange considering Toyota was in the neighborhood and had Type IV, but the owner (and his wife) was a stickler for fluids just like me and eventually took the Harriers to Brazil for his next assignment but heard nothing more. However, I wouldn't want to test it myself.

A/F sensors (don't worry about the O2 sensor as far as performance, that is only emissions related) can get accumulation on them. My own theory is that they go bad for the most part in the RX300 due to their placement before the precat (this is true on a lot of vehicles), but the precat is way up the pipe (a.k.a. close to the A/F sensor) and I think that the pressure/heat must be more there than on other exhaust designs on other vehicles. The 1MZFE Solara (except those that are California spec) does not have precats and I don't see nearly (nor when I talk to Solara owners) the number of A/F sensor issues that I see with those 1MZFE engines that do have the precats. I have only had one A/F code over the years and I haven't had precats since my fiasco with Mexican gas destroying one and also causing an issue with my main cat (was noticed on a gas analysis machine).

thomas1

Yes I purposely said Mobil 1 synthetic is NOT compatable. I went on their site and they state that flatly. It is working great in my Ford truck however.

archangels

are you talking about mobil 1 engine oil change or tranny oil change of mobil1 is not compatible? also how many quarts of tranny oil i should buy? thanks

thomas1

my bad, I was talking tranny oil. You cannot use Mobil 1 ATF in our lexus....
by the way It takes 4.3 qts of Toyota Type IV to do a drain and fill on the AWD RX300. So buy 5 and enjoy. The fluid change post in the beginning of this forum has great pictures and hints. read it.
https://www.clublexus.com/forums/sho...d.php?t=220061

archangels

is rear af sensor very hard to get to? thanks and you recommend spraying wd40 on the nut before removal?

archangels

i recieved my o2 sensor today and 2 a/f sensors, i will take pics of the old one to show how dirty i guess it got? any suggesstions on rear af sensor? any pointers before i begin? my mechanic saw me rolling in a lexus and business has been slow gave me a quote 200dollars to install both af sensors and 02 sensors? for direct plug n play i thought that was steep the 200 dollars could go to a nice magnaflow or something like tranny oil change and etc? is this all easy? i am worried about the rear on i forgot who said rear af was tight?

archangels

do you change diff oils and transfer case oil same time as 15,000mile tranny oil change

archangels

i first tried the steps lexmex said, then read a folk who har same p0171 and p0174, they said they change iacv valve sensor, so i figured maybe spray throttle body cleaner on iacv valve really good i saw rubbe hose with minor oil residue from crankcase vent hose to air intake hose so i figure the iacv was dirty with oil sludge , i did every procedure then gave full throttle looks like it did the job, no cel light no vsc light nothing, idels better more reponsive, accelrates wih ease seems faster , shifts smoother, i guess i did not need the 02 and af sensors, what you say lexmex if code is ok i wouldn;t need thesensors? or changing a/f sensors will increase mileage on gas anyways if changed? thanks

Lexmex

I would wait and see if the light comes back (and keep the sensors handy for later if they don't because usually when I start seeing errors in these vehicles happen, even if they go away, eventually the light comes on for good, A/F sensors are going on the way out. My MAF sensor also did that in December and eventually I replaced it.

Transfer case and rear differential can go 100k miles, I imagine a lot of people can do this with their RX, though I am now going to go on an every 2 year schedule now that I am at sea level. For normal driving I would do it about 1 time every 30K. Royal Purple 75W90 gear oil is my favorite, though I am using a Pennzoil synthetic for the moment as a test.

The A/F sensors can be a major PITA to remove off the manifold. Several have gone through this process and they can chime in.

archangels

ron if 02 or af sensor bad wouldn't the ob2 pick up a code to show that particuler part as being bad? i got a ststem ob2 scanner monitor said 02 sensor ok o02 sensor heater ok catalitic ok ... i think i bought an advanced scanner the only feature i did not have was a live scanner 0b2 expensive 300dollars however i wanted it as a good investmentalso what does a live scanner do? i bought mine at preppyboys

archangels

lexmex even if cleaning procedure fixed the problem the previous owner owned for about 7 years seems long to me... returning this i would lose 15% restocking fee so i might as well change them anyways, i couild imagine how dirty they are , if i change them out at least i know i will not have to forawhile, i forgot who said this but one folk said they changed them out even though it was not the problem and experience more efficient performance and extra gas savings miles per gallon, i need your expert advise i might have my bro in law help put them on, do i spray wd40 on them to loosen also do i buy a oxygen sensor socket and that big 2 feet long socket wrench what ever its called i think torque wrench for better levrage? thanks besides o2 sensors af sensors and maff is there anything else around that circle that would need or could be changed? thanks buddyalso i saw the o2 sensor goes up how do you take off rubber gromet and where is the connector someone said take back seat off and pull capet up and its there how you pull out seat on back and etc thanks also you know size of 02socket and for the wrench part what is 3/8drive and 1/2 drive? thanks