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Car fuel economy meter counts backwards

Hello there,

I would like to ask, after I have changed a new battery my car electronic live fuel consumption meter runs backwards.
Example, max live fuel consumption is 30.0 L (if i press gas pedal to ground in first gear) and when I drive normally in 5th gear its 5.5 L.
But now it show in reverse, when I drive normally in 5th gear its 24.5 L. And when I speed in 1st gear its 0 L or 0.5 L. … It seems values in car computer got reversed?

I have Opel Agila B 2009 or Suzuki Splash *same cars

Anyone with some experience in this?


Yes,it doesn’t make sense. You probably fried something when you installed the new battery. It looks like the polarity is reversed.


Could it have switched to miles per gallon?


Thanks for replies.

I think, I might have touched jump start cables together… when the battery was dead.
All the rest in the car computer works fine. Just fuel consumption meter polarity has reversed… wow :smiley:
Hmmm… is it costly to fix? Do I need to change whole sensor or?

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Is “I think, I might have touched jump start cables together…”, the same as “I seem to recall touching the cables together”, or, “I did touch the cables together” ? :face_with_raised_eyebrow:

How long ago did you change the battery and possibly initiate this problem?

The reason I ask is I’d be afraid that something else besides that economy meter could have been damaged. Carefully monitor for other anomalies.

Obviously (or not), “modern” cars have sensitive electronics and great care must be taken when working with battery cables.
:palm_tree: :sunglasses: :palm_tree:

While a fuel economy meter is a nice feature to have, I would advise that you not waste your money on repairing this problem with your 11 year old car. That money would be much better-spent on scheduled maintenance, and on repairs that might be needed in the vital areas of the car.

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I’m betting the algorithm is maxing out on highest consumption due to the values getting reset when power was lost. The normally low amount is high. Which it would be without long term averaging. The highest consumption rate is probably out of range and that’s why it looks goofy. A lousy implementation if that’s happening. Just give it some time to develop long term averaging…

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I think @texases has the correct answer. Check your owners manual, it may well be reading mpg or mpkm instead of L/100km

Yesterday, old battery died, hooked up jump-start cables and touched them, small spark came out. Started the car and drove out the buy a new battery. Changed it and the problem appeared.

Seems that everything works fine, just the live counting values are in reverse, the values are realistic tho, just from the other end.

Not in L/miles that is for sure. Because, after 30 min of driving, it counts Average Consumption as 25 l/100 km for a 1.0 engine car. Usually average is 5.0L/100km. hahaha

It is just weird that shouldn’t it blow up the fuse in first place? NOT make the sensor work backwards? :smiley: I hope I won’t have to change whole ECU.

Thanks for replies! I will post if I get news

Exactly. The normally low amount is high. As if the algorithm has reversed…

Actually, you are right. I just need to read it in reverse… 25L is 5L and etc. hahaha

I don’t think it’s reversed.

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Both of our vehicles show several things - Temperature - Miles to Empty - Avg speed - Avg Miles per gallon - current mpg . Temp and Miles to Empty are the only ones I care about . The current used goes up and down so much to be useless.

I hear you. I think I’ve got that crap on some of our cars, too, but it’s all useless to me, like so many other things added to cars. None of it helps me while driving.
:palm_tree: :sunglasses: :palm_tree:

I see your point. But aren’t Miles to Empty are influenced by Avg Miles per gallon and current mpg? In my case it makes Miles to Empty useless :slight_smile:

Just because you have 1/2 tank left you don’t really know how far you can go . The miles to empty does a very good job of correcting the estimate as your driving pattern changes. Of course like other people I never let my tank get below 1/2 full. Have you not noticed that the avg mpg can change if you return to stop and go from highway driving . Do you not reset with each fillup ?

Today I took the car for a 20 min ride and everything went back to normal. Funny problem.

Thanks for support guys :slight_smile:

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