I have recently been told that topping off your fuel tank will cause your Oxygen sensor to rapidly fail. I have no idea if there is any merit to this or not but I do top-off my tank. This may be a bad habit, but I have a good reason; by topping off the tank you know it is full so you can accurately compare gas mileage between tankfulls instead of doing the average across several tanks.

Any technical experts with a thought on this?

2006 MCC CR/Blk

 

The oxygen sensor is on the exhaust pipe monitoring the oxygen level in the exhaust gasses. It is not in the fuel tank. A full tank of gas does nothing to the exhaust fumes in any way shape or form.

 

I've been topping my tank for 3 1/2 years with no sensor problems. I do it for the same reason you mentioned...to accurately calc my mpg rate.

 

I've topped off my gas tank every time I fill up, and never had any kind of issues.

As previously mentioned, O2 sensors have little to nothing to do with the fuel tank.

 

Whoever told you that should rapidly be corrected.
Now if you top off with LEADED gas...

I do it for mileage calculations, and because I want to spend as little time as possible in gas stations.

 

...but it will cause your kids to be born naked......

 

Who comes up with stuff like this?

ALSO if you never put fuel in the car, it will cost you nothing in repairs. Never wory about those costly replacement parts again. Go to the dealer? What dealer? Never see those "This is normal" people again or for that mater you don't have to see anyone, doctors, lawers, therapists, just the pizza delivery guy. Aaaah, does it get any better than this?

 

Total BS.. The O2 sensor sees exhaust gases the same regardless of how full the gas tank is. A bad fuel mixture or contaminated fuel can lead to O2 failure... The amount of fuel in your tank or the frequency you fill it has no effect on the O2 sensor.

 

As said earlier, the O2 sensor is in the exhaust. Actually, I believe there are two of them. One before and after the catalytic converter. If anything topping the tank should avoid problems because you would be less likely to get condensation in the tank.

 

quote=2Miniacs]...but it will cause your kids to be born naked......[/quote]

 

OK great! Thanks for the info, I now have the ammo I need.

It's true though, all of my kids were born clothing-free.

 

the only thing that can go out because of total top up of fuel is your carcoal canister its made to hold gas vapors only not liquid. and with leaded fuel the cat will become cloged up i have not herd of o2 sensors going out with lead but then agian they dont sell leaded fuel no more. i also top up and minie is fine

 

Sure they do sell Leaded gasoline. Go down to your local Motorbike/Offroad/ATV shop and ask for it. They have it.

 

In many parts FL you just have to go to the pump without any cars next to it (often carried in the same manner as desil fuel), once you get away from the major population centers of course.

Never topped off and had my O2 sensor act up, but the issues went away on their own.

 

Why top off at all??? How much extra gas do you get that way? Don't you risk sending gas to the canister or back through the vapor recovery lines?

It's hard to imagine that topping off is that much more exact than just stopping with the automatic shut-off....

 

That's nothing to worry about...but you really ought to consider upgrading to cross drilled brakes lines

 

Yes...........can damage the vapor recirc system.

See http://www.cartalk.com/content/eco/tips.html
and http://www.epa.gov/donttopoff/

 

Sort of OT but ever try and fill your Mini with the motor running? Won't work...the pump keeps cutting off as if the tank was full