lebAaron32

Hello everyone. My name is Aaron and I'm relatively new to these forums. I've owned my rx300 since last August and it hasnt given me any problems til now.

Two nights ago I was pulling onto my road when my cel came on and the traction control light. The next day I drove it to work and checked out the codes. The first shot of codes was as fallows:

p1150 - A/F rat. sensor cky range/performance malf. b2s1
p0125 - Insufficient cooant temp for closed loop control
p0171 - system too lean bank 1
p0172 - system too rich bank 1 (:O)
p1155 - Af ratio sensor heater ckt malf b1s1

The p0125 I considered to be just a parameter that had been spotted as the code was set because I got gas right before it happened so the car had some time to cool. Bank one being too rich and too lean had me a little thrown off but i looked past that for now.So after that tidbit I did some searching around and found that there had been issues with emissions problems causing other lights to illuminate (tcc) for example. I also read about that pesky vacuum hose on the air box. I planned on changing my oil and rotating my tires last night so while doing so I did a bit of a visual on just about anything i could get my hands on. I noticed that intake tubing coming off of my airbox (after the MAF) was slightly loose (probably because some hold down screws are missing for the airbox). So I tightened that and continued my search. I found an exhaust leak soon after and its located down from where each downpipe meets right on the flange.

After my visual i cleared the codes and drove home. Omw home I gave it a little gas going down my road just to see what the lex had so say. I pulled into my driveway and checked the codes again. Now I had found some of the previous codes and also the misfire codes p0300 (random) p0302 and p0304.

My question here as my mind is trying to make sense of all this is what exactly is the classification of the oxygen sensors. Ive been looking around this forums and i dl'd some pdfs and what not but all ive gotten is that the o2s all the way in the back of the car (post cat) is b1s2 so im guessing precat is b1s1 and then the two coming off the headers and b2 sensors 1 and 2 respectively. I'd like to know which bank 2 sensor is which. I have a hunch that the right side of the engine is b2s1 but i cant confirm it.

Im a mechanic myself but i am broke and can't afford a big repair bill with massive diag time at a shop. I'm thinking atm that I will repair the exhaust leak and go from there. Could the exhaust leak have caused such a misfire sequence in just one bank? even if the leak is after both bank two sensors?

Also the rpms dip up and down when i am at idle, especially when the car is in reverse. Its not by a lot maybe a 150 to 200 rpm variance but enought that i notice it. And every other time i start my car the trac off light is on. Its not every time that it comes on.

If anyone has any ideas please let me know immediately!

bearbrew

Here is some information about the P0171 code that Lexmex wrote a couple of years ago.
This is the checklist for a P0171 code followed by my comments,

-air intake hoses (check the ones by the airbox and the IACV valve)
-fuel line pressure/injector blockage (run some fuel injector cleaner through the system, Redline fuel system cleaner (Pep Boys has it) is the best stuff in my opinion in an all-around cleaner
-A/F sensors (doubtful), but sometimes as a result of a crack somewhere on the exhaust itself, either right off the manifold or underneath the engine), this doesn't necessarily mean something is bad with the sensor, just that it detected something out of whack.
-MAF sensor (needs to be cleaned)
-engine coolant temperature sensor (rare), because other codes P0115, P0116 would be involved
-exhaust system- as mentioned above by a/f sensors

I have a question, have you tried disconnecting both battery cables for a few minutes, then reconnecting them and then code still comes back?

On the A/F sensors and even ignition coils, I'd highly (and I do mean highly) suggest you stick to Denso. We've had enough members use something else and eventually wind up with some issue. www.rockauto.com usually has some good prices for parts and I have used them over the years.

If there was an issue with the A/F sensors or even a coil, something other than P0171 would show up. P0171 can mean (as I suggested above) some issue detected by the A/F sensors themselves (bad gas, exhaust leak letting in air, etc.).

The MAF is located aft of the air filter box. Two screws and an electrical connector. Clean with electrical contact cleaner. There is a write-up on the procedure here on the forum.

Disconnect the battery for a few minutes and see what codes may come up. We can deal with them later.

lebAaron32

Thanks bear, yah i found a small leak after the maf, i tightened that up and its good to go now. I appreciate you taking the time to respond to my post. I know the lean rich codes are pretty general so i didnt make too much of them. im pretty sure the exhaust leak i have is the stem of this problem. The only thing throwing me off i'd say is that my traction control light keeps turning on and off periodically while i drive. (off hand i attribute this to the fact that possibly if there is an issue with A/F ratio's and fuel control, traction control could be put on hold because some cars cut off injectors to decrease engine rpm to help control traction) but im not 100% on that. That as well as the codes i have for the heater circuit malfunctions on the o2 sensors. I know they'd throw a code for lean rich mixtures if something was outta wack from the intake to the exhaust but the heater ckt issue seems pretty specific. I found a pdf on this site with some testing procedures for the o2 heater ckts so if that code hangs around ill throw the dmm that as well i guess. i think the only thing stopping me is that the genius who designed the car decided to stuff the post cat o2 in the most ridiculous location. It seems to be one of those issues where its there but you have to look deeper than just that. From here i'm going to try and fix my exhaust leak on my own, disconnect the battery and see what codes come back. I think the misfires that occured threw my mind is a bit of a tizzy and it made me over think this haha. After all....it is a lexus. lol

Sincerely, Aaron