Since my car was new, I was keeping track of tank mileage on trip odometer A, and lifetime mileage on odometer B. In other words, I never reset B. At over 11,000 miles, it was at 34.4 mpg. I recently checked the reading at my last fill-up: Lifetime mpg 0.8. Something's obviously not right with that... Even if it had been inadvertently reset with the reset button, it would have read somewhere around 30 mpg, and probably higher, corresponding to the mpg since the reset. I left it alone, and checked it again at the next fill-up: 1.8 mpg. So it's slowly creeping back up.

It appears that what happened is that the total miles traveled reset itself, but the total gallons used continues to be tracked and didn't reset. This happened at some point over 11,000 miles. So the trip computer now thinks I've used hundreds of gallons of fuel and traveled just a few hundred miles, and therefore reports 1 or 2 mpg, lifetime.

Anyone else experience this kind of reset? Maybe the trip computer can only handle a reading no higher than 11,000 and some miles, then goes back to zero? It never happened on my Civic, however. I can live with it, of course.

 

Is your real odometer still correct?

Very curious as to what Honda says about it.

 

Yes, the real odometer is correct and was not affected. Trip A was also not affected. Interestingly Trip B, as displayed on the dash, also did not reset. It currently reads 883.7. The odometer reads 11884. So Trip B has not been reset since the car was new.

From when the car was new until now, I have used about 347 gal of gas (calculated based on avg. mpg). The trip odometer currently reads 883.7 miles. Using those 2 figures gives 2.5 mpg. But avg mpg on Trip B is reading 1.5 today. (I think it might have been 1.3 before and not 1.8 as I reported in my orig. message, and the average is still therefore going up). I thought it might have exceeded its calculation capacity at exactly 11000 miles, then started over, but that's not the case. It had to be somewhere over 11000 miles. Based on 1.5 mpg and 347 gals of gas used, it was about 520 miles ago that it reset for its internal calculations, or at about 11360 miles. (That is just approximate due to rounding errors in the 1.5 mpg figure, and the approximate nature of the 347 gals used. It might be plus or minus 50 miles from 11360 when it reset).

I filled up the tank most recently at 11178 and 11625, and therefore reset Trip A at those odometer readings. So the "mystery reset" was in between those fill-ups, and I'm pretty certain it wasn't anything I did.

I think if I went to the Honda dealer with all this, they say "HUH?" and not have a clue. They can't "duplicate the problem" so couldn't fix it unless other people have reported it and a fix exists. It could also be a one-time electronic bug that will never happen again. It's also more of a curiosity that a real issue. I have owned my HAH for long enough that the lifetime mpg figure wasn't changing much anyway, so having to start it over isn't a big deal.

 

I'm at/near 8500 miles now. When I hit 11,000 I'll keep an eye on Trip B (I haven't reset mine either) and report what happens.

I don't think the Honda techs really get into the engineering of stuff like the trip computers. If Honda does have some sort of limitation in how it reports MPG, I doubt going into any Honda dealership would get you any answers. And since it doesn't affect the normal operation of the car, I don't think they'd spend much time researching on how it operates. Too bad we don't know any actual Honda engineers. It would be cool if Honda offered a seminar like Ford did.

 

I had the exact same thing happen to me a few fill-ups ago. In fact I believe mine also read .8 mpg on trip B. Kinda made me mad at the time. I'm now at 12.450 miles on the odometer, so it would have been around the same mileage as yours when it occurred. My current trip B LMPG is 29.8, but it should be 33.4. It was tracking my pump calculated mpg very closely.

Rich

 

I have found, at least in the Civic, that the trip computer is not very accurate. I just filled up and the trip computer understated my MPG by 4 percent.

 

After thinking more about this today, I discovered that I lied yesterday. I forgot that I had reset trip B. I guess I was more upset than I originally remembered. I wish that I hadn't now just to be able to see what would have happened to the LMPG reading.

Rich

 

My HAH has over 14,000 miles, the B trip meter has never been reset and is still accurately reading lifetime MPG.

 

Mine was up to 1.9 mpg today, and I gave up on it fixing itself, and reset it. It immediately started acting properly, and over the ~15 miles to home, it ended up at an average 39 mpg. So it's currently acting properly, after the intentional reset.

It looks like the 11K+ mile partial reset was unique to my car. I'd guess it was a one-time glitch, but who knows.

Actually, I'd like to have 3 trip meters. I'd use one for tank to tank mpg, one for lifetime, and the third for playing with on various driving segments. Maybe now that I've lost the lifetime figure, I'll starting using Trip B that way.

 

I think maybe my last post was a little unclear. This reset did happen to me. I just reset my trip B before you did. I guess we'll see if it happens again in another 11K miles.

Rich