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Fuel reading incorrect

10K views 20 replies 14 participants last post by  Insighter 
#1 ·
So I had a weird thing happen yesterday. I decided to top up the gas (that's not the weird part). I wanted to see what the combined total range was, because we are mid-winter here (Quebec). I was able to put in just over $7 in the tank (cost of gas = $1.08/L)...so about 7L.

BEFORE I topped up the tank, the HV (ie gas) reading was at 350km, and the gauge (bars) on the right showed about 2/3 tank. After I filled up (and I did fill up...in fact, I inadvertently spilled a bit trying to top it up), I drove away...only to see that the gauge was still showing the same 2/3 full, and the range was still 350km! As I approached our local village....the gauge on the right slowly crept up, one bar at a time, to eventually show a full tank....literally at about 1 bar per km. Weirdest thing I have EVER seen in any car. Even weirder? The range refused to budge from the before-fill-up 350km.

I figure it's a computer/electrical thing...but I was super disappointed to see that when I went out today, it is still reading 350km.

I have no idea what to do. I mentioned it to my husband (who works at Ottawa Honda) and he said to take a photo and let them know (he always says it's better coming directly from the customer, not the salesperson like him!).

Before anyone says "oh maybe that's what the range is, during a Canadian winter", there is no way. The highest range I got last summer (when we bought the car) was 690km combined. As of late, in winter, it has been about 500-550km combined. So I know 350km is way off. More to the point, it's the fact that it never moved after filling up.

Has anyone had this happen before?
 
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#12 ·
I have had my 2018 Clarity Touring for less than a week. The fuel tank was full when I got it but the EV was on zero. I drove about 45 miles then charged it overnight. Ran full EV for the next two days. Ran about another 40 miles on gas only, EV at zero, charged overnight and ran quite a bit in sport mode today.

My fuel gauge has never moved and my HV shows 266 range ALL the time.
 
#4 · (Edited)
I have not heard of what you described about your fuel gauge taking about one km per bar to move up before reaching full after a fillup. Then again it's possible that it sometimes happens especially in cold weather and people just don't notice or haven't said anything. It is normal that fuel gauges don't always immediately display full after filling up. Although if I understand correctly yours took several minutes to go from 2/3 full to full. That in itself may not be a problem as long as the fuel gauge is otherwise accurate in showing how much fuel you have.

The HV range is just a calculated estimate affected by various factors and not something in itself to worry about. There was a TSB back in June 2018 that referred to a software calculation error in calculating HV range, but that problem would not cause your fuel gauge to act like you were experiencing, because the fuel gauge is an actual gauge based on direct readings it is not an estimate like HV range is.

Next time you fill up see if it happens again, and if possible keep track of the actual time it takes to go from 2/3 or whatever to full. To keep things from getting confusing if you post about it again or talk to a dealer about it, I would suggest to not mention HV range but only describe the fuel gauge symptoms, as the fuel gauge is a critical instrument whereas HV range is only an estimate, and including it in the conversation will unnecessarily shift the focus of answers that you get to HV range whereas the more important question is whether your fuel gauge is working correctly. Which maybe it is but I would recommend to focus only on the fuel gauge for now and keep track of how it works over the next few fillups.
 
#6 ·
Yes, Happened when I just topped up to put in about 1 gal. Did not correct until I filled up the next time. Has not happened since, but I wait until the tank is more than half empty.
Yes, same here.

This appears when fuel is refilled with a small amount of fuel.
Fuel level reading eventually catches up.

I think it's a vacuum pressure issue myself.

To avoid this, I always fill up at least half a tank or more.:wink:
 
#8 ·
I had the same thing happen to me. I had about half a tank when I filled up. The gauge slowly came up to 3/4 tank and then stopped. It never went any higher the rest of my trip home, a few miles. I intended to take it to my dealer the next day to have it checked but when I powered up the next day it was showing the full tank that I knew I had. I have not had the problem again. 2018 Touring model
 
#9 ·
similar issue

I had something similar. The tank was almost empty when I went to refill it. I was only able to get 3.5kg of H2 into the tank. I pulled away to let another car fuel and saw the gauge only showed 2/3 full. I pulled around to try refueling again but the pump only allowed 0.2kg to be added. The gauge stayed at 2/3 until the next day. The tank of H2 only gave me a range of about 200 miles before I returned to add a complete 5.0kg to the tank. It has not happened since this one time.
 
#10 ·
I had something similar. The tank was almost empty when I went to refill it. I was only able to get 3.5kg of H2 into the tank. I pulled away to let another car fuel and saw the gauge only showed 2/3 full. I pulled around to try refueling again but the pump only allowed 0.2kg to be added. The gauge stayed at 2/3 until the next day. The tank of H2 only gave me a range of about 200 miles before I returned to add a complete 5.0kg to the tank. It has not happened since this one time.
We are discussing the PHEV not FCV. There was a post on the FCV forum where someone mentioned that their car won't accept as many kg of H2 during winter. Not exactly the same as what you experienced so I don't know if it is related

https://www.clarityforum.com/forum/2471-post7.html
 
#13 ·
So I had a weird thing happen yesterday. I decided to top up the gas (that's not the weird part). I wanted to see what the combined total range was, because we are mid-winter here (Quebec). I was able to put in just over $7 in the tank (cost of gas = $1.08/L)...so about 7L.

BEFORE I topped up the tank, the HV (ie gas) reading was at 350km, and the gauge (bars) on the right showed about 2/3 tank. After I filled up (and I did fill up...in fact, I inadvertently spilled a bit trying to top it up), I drove away...only to see that the gauge was still showing the same 2/3 full, and the range was still 350km! As I approached our local village....the gauge on the right slowly crept up, one bar at a time, to eventually show a full tank....literally at about 1 bar per km. Weirdest thing I have EVER seen in any car. Even weirder? The range refused to budge from the before-fill-up 350km.

I figure it's a computer/electrical thing...but I was super disappointed to see that when I went out today, it is still reading 350km.

I have no idea what to do. I mentioned it to my husband (who works at Ottawa Honda) and he said to take a photo and let them know (he always says it's better coming directly from the customer, not the salesperson like him!).

Before anyone says "oh maybe that's what the range is, during a Canadian winter", there is no way. The highest range I got last summer (when we bought the car) was 690km combined. As of late, in winter, it has been about 500-550km combined. So I know 350km is way off. More to the point, it's the fact that it never moved after filling up.

Has anyone had this happen before?
I am driving a brand new 2020 Clarity basic that is having the same issue. Has anyone found a reasonable solution?
 
#14 ·
So I had a weird thing happen yesterday. I decided to top up the gas (that's not the weird part). I wanted to see what the combined total range was, because we are mid-winter here (Quebec). I was able to put in just over $7 in the tank (cost of gas = $1.08/L)...so about 7L.

BEFORE I topped up the tank, the HV (ie gas) reading was at 350km, and the gauge (bars) on the right showed about 2/3 tank. After I filled up (and I did fill up...in fact, I inadvertently spilled a bit trying to top it up), I drove away...only to see that the gauge was still showing the same 2/3 full, and the range was still 350km! As I approached our local village....the gauge on the right slowly crept up, one bar at a time, to eventually show a full tank....literally at about 1 bar per km. Weirdest thing I have EVER seen in any car. Even weirder? The range refused to budge from the before-fill-up 350km.

I figure it's a computer/electrical thing...but I was super disappointed to see that when I went out today, it is still reading 350km.

I have no idea what to do. I mentioned it to my husband (who works at Ottawa Honda) and he said to take a photo and let them know (he always says it's better coming directly from the customer, not the salesperson like him!).

Before anyone says "oh maybe that's what the range is, during a Canadian winter", there is no way. The highest range I got last summer (when we bought the car) was 690km combined. As of late, in winter, it has been about 500-550km combined. So I know 350km is way off. More to the point, it's the fact that it never moved after filling up.

Has anyone had this happen before?
😀😎HERE IS THE SOLUTION:

As suggested earlier by one other forum user, you will need to disconnect your 12v battery for a few minutes (I left mine sit for several hours). After re-connecting the battery you will see a series of warnings appear on both your dashboard as well as the infotainment system. Simply ignore all of them, and drive you vehicle as you normally would for a few minutes (I drove mine for about 5 miles or so). You will notice that all the warnings will disappear and the system will be back to normal with an accurate fuel range reading. To reset your infotainment system, simply push and hold the power button on the screen itself for over 2 seconds, and that will restart the system. After that, you can simply configure all of your dashboard options as needed or desired. That's it! BTW the techs at the dealer's service center didn't have a clue, so don't be surprised if you get the runaround. They simply do not know, and Honda has not brought them up to speed on how to resolve it.
 
#18 ·
What eventually happened for both of you for this problem, @Madmartigen and @EV Nerd ? Did you need a repair or how did you fix the problem?

This just started happening with my '20 Touring. My EV range and gauge are functioning normally, but my gas gauge and range (HV range) are stuck at nearly full for the gas gauge, and 269 for the HV range, even though I am using some gas.
 
#20 ·
My gas gauge got "stuck" after I filled it up to the top of the fill tube. I added more gas (two or three more "clicks") after the nozzle shut itself off. This is what I've done with ICE vehicles for the last 50 years of driving, and it's never been a problem.

After researching for a bit (on the Web), IIRC, I saw a Reddit post that indicated that this "stuck" condition appears to be caused by overfilling the tank. It's possibly about how the Clarity PHEV's gas gauge sending unit works, or it may have something to do with the way the vapor recovery system works.

My "fix" was to drive it in HV mode until I knew the tank was about two-thirds full...well below the fill tube. I then did the "10mm reset", which is to loosen the 10mm screw on the 12V battery's negative terminal for an hour or so. Then I reconnected it and drove it for a while. The gas gauge dropped down to about two-thirds, and the range number dropped too.

Others have reported that the gauge reset after they put more gas in it, after they drove it and knew they needed more gas.

Mine appears to be working properly now.

My advice is to not top off the gas tank after the fill nozzle shuts off.
 
#19 ·
What eventually happened for both of you for this problem, @Madmartigen and @EV Nerd ? Did you need a repair or how did you fix the problem?

This just started happening with my '20 Touring. My EV range and gauge are functioning normally, but my gas gauge and range (HV range) are stuck at nearly full for the gas gauge, and 269 for the HV range, even though I am using some gas.
I have a 2021 Clarity PHEV that I got 3 months ago and this week it started this same behavior. Mine is stuck at 274 miles of range and the gauge hasn't moved even though I have used a fairly significant amount of gas in the last few days.

I see the solution of disconnecting the 12v battery, and I will do that (Thanks for posting) but I would like to try a few other things first. I will update if something different works or if the 12v disconnect is the only workable solution.

Edit to add: Progress! I just opened the fuel door and fuel cap. I then put the car in HV+ mode. Once I did that, it started working again. Of coarse, this is only a partial solution because it didn't drop down to where it "should" be. I would guess that it is still about 40 miles above what it should be reading, but at least it is dropping when the engine runs either in HV or just if I accelerate enough that the engine runs in Eco or Sport modes.

**Second edit. Further update. Once I refilled the tank to full, it registered the full tank and changed the range estimate to the correct number. Since then, it is working correctly again.
 
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