I posted a few weeks back that my 'Check Engine' light, the 'VSC' light and the 'Trac Off' came on. I took it into the Lexus dealership and the trouble code was P1135. The culprit was a bad Air/Fuel Sensor and they replaced it under warranty.

Today all the same lights came on again. I suppose it's possible the Air/Fuel Sensor they installed was faulty. We shall see. This happened earlier today at Myrtle Beach. Now I am home and my 100k mile warranty expires in 560 miles. I am at 99,440. I am now afraid of what may happen after I surpass 100k.

 

You've established that the problem began within warranty - if you keep having the same problem, you should be well covered.

 

Get it checked out while you can. It is possible the installation was bad. Another theory (and my uncle has seen this on cars down here) is that one A/F sensor is replaced, but since the newer one has a higher efficiency (and maybe of a slighty different design as occurs over the years), two A/F sensors don't work in tandem as well with the ECM. This is a little rarer condition, but I think it probably was something not installed right.

 

It's being fixed right now. Evidently the OTHER air flow sensor is now bad. They said it was coincidental that they both failed after 7 years within one week of one another, but I'm not so sure. The first one controls the air flow going in, this time it was the one controlling the air flow coming out, so they said.

 

Well, that one reading the air going in is the MAF sensor by the airbox, but the one reading the outbound flow are the two A/F sensors on the exhaust manifolds.

 

As of yesterday 11-19, I got the same dash lights again. This is three times now. Unfortunately for me I am now out of warranty and the dealer said they will only cover it if it pulls the same code.

 

Well surest way to check is go to an AutoZone and have it checked for the code or any mechanic who has an OBDII sensor.

Only things for that code are the sensor itself, the ECM or a short. The only other thing offhand that can cause this code is something dirty going through the sensor but that is reflected indirectly by the sensor popping a CEL. There's not much I can tell you beyond that. One other way to notice is if MPG has not improved after replacing the sensors. Now, if that is the case, then something else is at play, perhaps in the combustion or intake chamber being dirty and and throwing some gunk by the sensors themselves (even if new).

Now, I'll add something from my recent experience. I have gotten one P1135 about a month ago, reset the system but it still seemed to lag a bit. I tossed in some Nology PowerBoost, http://www.nology.com/powerboost.html, something I have used before, on a half tank and full bottle, and combustion seemed improved right after that. I am certain probably my lack of running an air filter and all the gunk that flies in, including through my IACV had caused this issue. Apart from P0171s related to my air intake, no other issues.

When my A/F sensors fail for sure, I am going wideband.

 

did you ever get this resolved? My mom is having the same problem with her RX300 (2003). She is about to take it to the dealership, because we cant seem to find any answers.

Thanks,

 

Lex,what is wideband? Dummy sensors?

 

Never took it in and it went away after a few weeks. Fuel economy is down from 21.7 to 20.5 but that would be winter mix fuel.