[2007e90325i]

Hi everyone,

I just bought my %100 stock E90 325i at 175.000km and accidentally put 28 liters of E85 on 5 liter remaining E10. After 60 km drive with moderate pulls, i realize my mistake when check engine light comes on!

I topped it with 30 liters of E10 just after check engine light comes on but fault was still there. Then i have to drive it 100 km and then topped it up with 20 liters of E10 again.

Check engine light gone just after couple kilometers after last fill. Nothing change in driving characteristics or on power during all this shenanigan.

Is engine and fuel system forgiving that kind of mistakes or should i consider to check something with upcoming regular maintenance? Is there specific reason for check engine light in that situation?

Please forgive me if i miss some posting rules. I checked many E85 topics before but they mostly gathered around mixing E85 intentionally or mods for E85 use.

Thanks for helping.

[ky0u]

Your light might have come on due to “lean condition” since you ran e85 on an car with a stock map. E85 tunes usually require more fueling from the pump in order to compensate for the less energy/vol than normal fuel

Reverting should have remediated the situation. Not sure what “moderate” pull entails here but you should be okay if your car isn’t throwing any further codes or running weird. 60km isn’t that much

[Brian86]

It'll probably be fine.

I suppose it's possible the lean condition could have burned valves or rings, but ethanol burns cooler than petrol so I think that's extremely unlikely.

If anything is damaged, it'll be very bad.... and there really isn't anything you can do about it.

[2007e90325i]

Thank you both for answers!

I will not fill it anymore before tank is empty to get rid of that mixture with easy drive and hope everything is fine.

Monitoring oil level could give some idea then, till there is 0 oil consumption so far for now.

[ky0u]

You don’t have to wait til the tank completely empties, just top off with fuel as normal once you hit a half tank or less. The concentration will dilute and should be more or less back to normal by the next 1 or 2 fill ups.

if you only had 5 litres e10 when you did the initial fill of e85 x 28l, your mix would have been at ~e73

Your following 2 fill ups would have put you at (respectively/roughly)

<e45
<e35