410225

Okay, my 2006 GS300 with 147k mi was throwing P0505 Idle air control code, which reading this forum directed me to replace the throttle body. I went to ebay and purchased throttle body with 61k mi on it for $50, instead of spending 700-900 for the new.

I have replaced the throttle body with battery negative cable disconnected. Connected back and drove to clear and reset ECU. So far so good.

I took the car out to work and on the way, throws same P0505 code.

What else could possibly throwing the code except the throttle body? MAF? I am stumped!

SILENTM

There is another component that may adjust the idle/runners. Its located on the back of the intake manifold (lower aluminum one). It opens up another set of butterfly flaps to each cylinder based on rpm and load. May want to check there also it also has a adjustment screw on it. Are there any symptoms? high or low idle

410225

Mine is high idle on start up and neutral, 750-800 drive idle. Can you tell me if it is on driver side or passenger?

SILENTM

its in the center all the way near the firewall, you can see the arms at the front of the intake manifold behind the coolant cap. it runs all the way to the back of the intake manifold, better access towards the drivers side near the pcv

410225

Thanks. I will check it out. Is that the usual way of adjusting idle? Just did not want to screw up more and cause more issue.

SILENTM

No i dont think this is the usual way to adjust idle, this is the only place i see that has an adjustment. most likely it will have to be adjusted electronically. normally the throttle will do a relearn the first few seconds you turn the key on, may have to leave key on for one minute before starting. You may have a intake leak also causing the high idle, so get the intake smoke tested

410225

I gave up and brought to dealer. Will see what they say

410225

Its been three days since dealer took my car in. SA called and let me know that they could not find the causing issue. Connected scanner and reading data, idle fluctuates in minimal way enough to throw code P0505. Checked PCV(new Lexus), MAF(cleaned), battery(new Lexus), TB(used 61k from ebay) all working properly. They are stumped as well. While doing this they gave me 2016 IS350 AWD to drive as a loaner. I want my car back!

410225

Update: Got a call from the dealer and they performed another thorough scanning and driving. CEL came back on with same P0505 and narrowed down to defective throttle body. I have explained that I have replaced the throttle body with newer used. They told me it could be isolated TB and regardless, it should not be throwing codes irregularly like this, so they have honored to replace the TB under Lexus warranty! I am charged with labor of $147.00. Also, I asked about TB cleaning, and they have advised not to force open the butterfly flap too much to clean but slowly open half way to clean. I will pick up my car tomorrow!

410225

Well, after two weeks and confirmation on issue with throttle body, ready to pick up my vehicle. Service advisor called and told me that CEL came back on again. They have escalated to Level 3 tech from Lexus corporate to read live data on the vehicle and finally isolated to faulty ECM. How the heck did they miss this one and replaced $800 TB in the first place? New ECM is $1,581! There is no way I am paying for that. I picked up my car last night and drove. CEL did not come back on. I have located 2006 GS300 AWD with 64k miles on it selling ECM for $140. I am going to replace the ECM and buy Techstream from Amazon and re-write the VIN to ECM.
I have sent fat complaint to Lexus about this.

Gotcha350

Not trying to be an *** but let me ask you a question....Do you have a warranty that covers your car? If not, I think you got a damn good deal at the end of the day. You got a new TB and only had to pay labor when the one you had was not the original one. Also, you did the samething....you threw parts at it without truly knowing what was wrong. A bad ECM is hard to diagnose and usually takes a good amount of time to determine that is the issue. Did they charge you a lot of labor for diagnosing a bad ECM? Once again, if they didn't then you got a pretty good deal for $147...

410225

Well, I convinced them to replace my used ECM to fix the code and dealer agreed to put on my used purchased ECM. Brought the car and two days later, they say it is not the ECM issue but my aftermarket alternator issue...... $470 to replace OEM alternator....

burny

what a cluster****

glsmoove

Did you ever find out the problem with this car? I dont know if you still it because thats been some years ago but my car is the same year and doing the exact same thing. Throttle body and MAF have been changed and I still get the code.