I have a 06 is350 with all of the options except the ML system. About 3.5 years ago I had shop install sub/amp by tapping rear wires going to the amp. Well everything worked perfectly until about 18 months ago when my car started doing the “Pop Pop” noise and no audio worked in my car. Well I had shop who installed aftermarket items look over system and they informed me it was a Lexus issue as all of the installed components were solid and passed all benchmarks. Since then Lexus has replaced the amp 6 times, audio control once, rear oem subwoofer, nav unit, and wiring harness that runs from front to rear of car. All of it works for about 30-45 days and the issue comes back. Lexus has given up and said they have invested too much money into this issue and refuse to honor their 12 month warranty anymore as they can’t find the issue. They at one time had possession of my car for over 4 months to find the issue and just decided to replace the harness and pray it worked. I’m looking for advice or help on how to resolve this issue permanently because Lexus won’t help and the corporate complaints department said they can’t do anything either. Next closest dealership is 2.5 hours away. With that being said here is what occurs....

start car and hear the “pop pop” from driver side rear deck speaker. No audio or anything works even if audio is turned off the accept nav screen doesn’t even make the beep noise. I will access service menu and dsp amp menu has numerous error codes of 74-40. I clear codes, restart car and sometimes it will come back on and other times it won’t. It occurs when humidity is high, it’s recently rained, or I come outside to the car being covered in water/snow. If the car is stored overnight in my garage it operates perfectly fine the entire next day. The entire aftermarket system was removed about a year ago and all wires repaired to oem spec. When Lexus has replaced amp its due to an internal fault in the amp. I am completely lost on how to possibly fix this issue.

i am considering taking the dealership to small claims because hey continuously Promised the repair fixed the issue, I paid accordingly, and then brought it back only to be told it was a different reason/part causing it.

Any help or guidance in this matter would be greatly appreciated and I have searched through the forums but haven’t found any similar post with ongoing issues after amp was replaced.

 

Sounds like the moisture issue most on here are complaining about. First thing, check for moisture down around where the factory amp sits. If you see moisture OR surface rust, water is leaking through the faulty "air flap" door right there behind the rear bumper.

 

Is it possible the faulty air flap? No amp has ever had water damaged when replaced just a fault. I’ve included a screenshot of one users solution

 

^After reading that, it makes me thing the amp itself internally has a grounding issue. If you try the towel "fix", let us know what becomes of this.