I am posting this as a Technical help thread for NELOC Lexus owners. I am in no way advertising a business or soliciting work. I am only on here to offering to help diagnose problems you may be having with your Lexus vehicles to get a jump on your repairs.

You can post your questions and/or info on your vehicles and I'll reply to them here!

 

I guess it wouldn't hurt to double check with you but I have a CEL on a 02 GS3, p0135 and p0430. I was thinking about just replacing the precat sensor with a new one and wiring an simulator for the post cat. or could something like an exhaust leak on that bank be causing both codes?

 

What mods do you have on the car currently ? Do you have aftermarket headers ? or are you still running stock catted headers? P0430 indicated cat efficency below threshold. Your best method is to replace all 3 02 sensors that are on the exhaust manifold to start. If the CEL comes on which it may you will need to replace the entire exhaust manifold assembly. IF you install a simulator and your cat is damaged you can cause more issues such as lack of performance which can cause more carbon to build up into your motor. It gets really deep after that.

Also after you switch the sensors only put 93 octane fuel, dont put 87-89 octane, The low octane fuel damages sensors.

Hope this helps

 

Background: 2001 GS430 on bags/19's

Since you know my car and did the diagnosis when it was at the dealer: For the wheel shake that I have, the service manage recommended the inner and outer tie rods. Since I am paying out of pocket for this one, can you tell me what else looked like it needed to be replaced, if anything (that's if you remember my situation of course).

 

Have a friend with a 1999 GS300, no mods

Following codes are displayed.

P0171
P0141
P0161
P0155

What do you think the cause of the codes are?

Thank you for the help.

 

It is the stock catted headers... but replacing all 3 sensors? Thats gonna get pretty pricey... Unfortunately for now I'm on a limited budget so I guess I'll start with the precat sensor on b1bs1. I'm glad you chimed in on using a simulator though, I didn't think a postcat simulator (electronic or mechanical) would have much of a performance impact. Thanks for the info.

 

Pmmed you about the car, Since you are running airbags on the car; It puts more tension on the factory settings of the suspension; I would recommend replacing the inner/outer tie rods, lower ball joints and upper control arms. These dont fail normally however when we have our cars modded the strain on the components wears them down prematurely.

 

P0171 - is a lean condition. Go to an auto parts store and purchase a MAF cleaner ( no brake clean!!!! ) clean out your sensor; check your air filter if you have an aftermarket air intake which has an oiled filter get rid of it and get a dry element filter for the intake system. Try this first and let me know how it works out for you.

P0141,P0161,P0155 - have to do with your 02 sensors. At this point your best bet is to replace all the 02 sensors and on top of that if you were putting a lesser grade fuel such as 87,89 octane. Stop!!. All lexus vehicles require 93 octane fuel. Your sensors will last alot longer and your pipes wont rust from the lead content in the lesser grade fuels.

GL

 

Replacing all 3 sensors is the best way to go however if you are strapped for cash you can replace one at a time. You will have to realize that your cats may be permanently damaged so expect to replace that as well. Depending on your mileage you may still be under Emissions warranty and get the Cats replaced, 02 sensors are not covered.

 

sounds good my man

thanks!

 

i have a 98 gs300 122k miles, 2 months ago check engine came on for bank 1 cat insuff. the car would bog out a little when taking off from a stop. car seemed to be under power, it didnt downshift when i floored it. I finally decided to change out the entire exhaust system: new exhaust manifold with cats (aftermarket), new down pipe, new y pipe, new mufflers. I also changed out one 02 sensor because it was cross threaded into the oem manifold. after the above parts replacement, the car seems to response much better, transmission would downshift when i floored it, no more check engine light. but once in awhile the car still bogs out when i am moving from a stop! is it tps, maf, the other 3 o2 sensors or maybe the transmission fluid?

 

It could be a number of things. My first suggestion is if you have an aftermarket intake with oiled filter element, replace that with dry element filter, Go to your nearest auto parts store and pick up MAF specific cleaner ( no brake clean, Brake clean destroys the speed density wire inside our mafs ). Also get throttle body cleaner and clean out your throttle body assembly; your plate could also be sticking; To clean out your throttle plate get a rag; spray the cleaner on to the rag and open the plate up and clean the plate and the surrounding bore. Lets start with that and let me know how it goes.

 

tach motor, thanks for the advise and i m goin to clean the maf and tplate this weekend and see how it goes. i think i should get a bottle of maf cleaner from the dealership. i heard using the wrong cleaner (brake cleaner) can mess up the o2 sensors and cats too?

 

MAF - controls a big portion of efi systems. If your MAF is malfunctioning it will send wrong signals to the ecm throwing the parameters off which can in-turn cause Cats and sensors to fail prematurely. This doesnt happen right away but does happen none the less.

Here is what the maf cleaner looks like and the one you should get.

http://www.autobarn.net/maairflsecl1.html

 

bumped; here to help. post up on this thread.