Last week I was driving back to my home. I saw my Lexus gauge showing 99.9 MPG. There is no check ENGINE in my dasbord.
is this reading faulty?
OR What should I inspect to get right reading.

 

Was your foot off the throttle?

 

maybe
I will try.

 

That happens when you go and pump gas or the cars ecu/ecm gets reset.

 

The gauge is in "instantaneous mileage" mode, which is your mileage at that second. You were mostly likely coasting or foot off the throttle.

 

Oh yah i forgot about that good call i havnt driven my ls in like 4 months =( i hate winter

 

One can only dream about that MPG being a reality with the LS430.

 

Guys, it's not because of the mode, or because of coasting. Somehow the calculation gets messed up. I have the same situation, and i ended up just using the range display, and not current mpg. It fluctuates really bad. Even the average mpg is just way off. From 12mpg to 327 mpg. Something us definitely wrong.

 

Not sure about that, maybe in your case. I just left the gym and put it to "Current MPG", let off the gas and it was showing 99.9 MPG as I was coasting. As soon as I pressed on the gas it dropped down to 18.* MPG.

OP I would suggest pressing the DISP 1 button and cycle through the options.

 

I think you have something wrong on your car. I can get 99.9 to show up on mine easily just by coasting the car for a couple of seconds. I think what Lexus should have done was to increase the sampling time out so that the value is a little more static. It's fine to change the value quickly when the data is being presented on a bar graph or other such means. I wonder if they offer an option in Techstream to change the duration? On my Honda ST1300 motorcycle, I believe the interval between updates is more like 10 seconds or so and that seems to work pretty well.

As they always say, YMMV ...

 

I repeat. The average mpg goes crazy. The average. No matter what kind of coasting you do. You cannot get an average of say..... 42mpg.