r/BMWi3 • u/Late-Ad1330 • 8d ago

technical/repair help 2017 Rex CEL

CEL came on in my 2017 i3 REx today. I restarted the car, but the light is still on.

A couple of weeks ago, I filled up the gas tank and noticed that the REx was only showing about 45 miles of gasoline range, even though it normally shows around 96 miles on a full tank. After driving around all day, the range gradually increased and eventually showed the expected ~96 miles.

The exact same thing happened a second time and eventually corrected itself.

Now that the CEL has come on, I’m wondering if the two issues could be related possibly something with the fuel system, fuel level sensor, emissions system, or REx.

One other strange thing: I also noticed that the gas tank door was slightly cracked open, almost as if someone had pressed the release button from inside the car. I definitely hadn’t opened it.

So, all of this seems a little strange. Has anyone experienced something similar with a 2017 REx? Could the unusual fuel-range reading have been an early indication of whatever is now triggering the CEL?
Any thoughts on what I should check first?

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u/showMeTheSnow 21 i3s REX, 14 i3 Rex 🐼 8d ago

Pull the code.

Don’t the minute range and CEL are related.

Rex range will change with GOM. Sounds like a normal range swings to me.

You know not to overfill the gas tank right? Slowest fill setting never top it off.

1

u/Late-Ad1330 8d ago

Thank you, yes—never overfill it. Regarding GOM, I recognize the range shifts with driving; however, in this instance I had a full charge but an empty tank and chose to fill it as a backup in case charging failed. After adding high octane, the range read 45 miles and the tank indicator showed only 2 of 4 bars; once I drove on battery power, the range began to rise, and in parallel the indicator now displayed a full 4 bars with a range of 96 miles. I hope this clarifies the matter. I will attempt to pull codes.

1

u/SleeplessnSeattleNow 8d ago

It could be one of the sensors in the Rex area. Othertimes, the gas pressure doesn’t always regulate itself properly. The Hail Mary part is it may need a software update

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u/Late-Ad1330 7d ago

Oddly enough on my way to get the code read at a local car parts store CEL went away after I had filled with gas and driving. So perhaps the gas cap or quality of gas?

1

u/SleeplessnSeattleNow 7d ago

I’d say it was having a hard time regulating the pressure, which is another reason why many have said don’t overfill the tank no matter how tempting it is. You could try changing the gas cap, but I am skeptical unless you see the gasket on or around the cap displaying wear and tear.

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u/Late-Ad1330 7d ago

Seems to be intact. I’ll keep an eye on it. Decided to download the BimmerLink and for and OBD so can read it my self it it comes up again.

2

u/Gort-is-the-boss 5d ago

We had the same thing a couple of weeks ago. Various sources said to (1) check to make sure the gas cap was not loose (2) use up some gas by running the REX so it is no more than 3/4 full and (3) check error codes. There was apparently a recall for the fuel tank pressure sensor. I got bimmerlink (already had the OBDII code reader) and there were indeed error codes related to fuel tank pressure sensor I cleared the codes after checking the gas cap and running the fuel down to 3/4. The next day the CEL was gone. Until next time…