Fuel reading incorrect - 2018 Honda Clarity Forum
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post #1 of 10 (permalink) Old 02-02-2020, 04:22 PM Thread Starter
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Fuel reading incorrect

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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post #2 of 10 (permalink) Old 02-02-2020, 06:51 PM
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There is a service bulletin to correct this issue. Not sure what the Canadian terminology and numbers are

Gary

2018 Clarity Electric (Vortex Blue)
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post #3 of 10 (permalink) Old 02-02-2020, 11:57 PM
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Allison

Here is a link to a thread which discuses this issue in detail.

https://www.clarityforum.com/#/topics/71

Post #25 has a link to 5 technical service bulletins (TSB) which you may need to refer to including the HV range issue. This info should help you figure out the Canadian equivalent.
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post #4 of 10 (permalink) Old 02-03-2020, 01:07 AM
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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.

Last edited by 2002; 02-03-2020 at 11:11 AM.
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post #5 of 10 (permalink) Old 02-03-2020, 09:00 AM
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Has anyone had this happen before?[/QUOTE]

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.
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post #6 of 10 (permalink) Old 02-03-2020, 09:56 AM
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Quote:
Originally Posted by Groves Cooke View Post
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.
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post #7 of 10 (permalink) Old 02-03-2020, 10:34 AM
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Quote:
Originally Posted by Groves Cooke View Post
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.
They said they were at 2/3 tank prior to filling up, not 6/7 tank like in your case. They said after filling up their fuel gauge slowly crept up to full over the next several km, it did not wait until the next fill up to correct like yours did. I think that's enough of a difference in symptoms to suggest that they may have experienced something with a different root cause than what you experienced.

Maybe it's all the same thing but maybe not. Both you and 4sallypat seem to have either put in a small amount of gas or waited until more than half empty. We don't seem to have any data points for how it is expected to behave when filling up at 2/3 tank.
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post #8 of 10 (permalink) Old 02-05-2020, 10:41 PM
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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
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post #9 of 10 (permalink) Old 02-06-2020, 04:02 PM
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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.
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post #10 of 10 (permalink) Old 02-06-2020, 05:34 PM
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Originally Posted by aquabio View Post
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
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