Car & Maintenance: Fuel Injection System Too Lean Bank 1 signal on car – could it be due to ethanol in gas?

My engine light lit up, and according to its code, it says "Fuel Injection System Too Lean Bank 1"

I have been (recently) purchasing my gasoline from a local Mapco turns out their gasoline has 10 percent ethanol (I read it on a sign there) could that be the reason why it went off?

Before I get a

My engine light lit up, and according to its code, it says "Fuel Injection System Too Lean Bank 1"

I have been (recently) purchasing my gasoline from a local Mapco turns out their gasoline has 10 percent ethanol (I read it on a sign there) could that be the reason why it went off?

Before I get a formal diagnostic, I want to change little things that may be the cause without shelling out a lot of money. My mechanic said it could be a vacuum issue, but I don't know

Best Answer:

Marjane: Most of the time it's because of a vacuum leak. It can be because of a bad MAF sensor, O2 sensor, exhaust leak between the engine and upstream O2 sensor or fuel delivery problem such as low fuel pressure, dirty fuel filter or a clogged/faulty injector. Best way to find a vacuum leak is with a smoke machine but most people don't have one so a propane torch, brake clean or a spray bottle of water works ok.

Other answer:

Marjane:
If the motor is a 4 cylinder, a lean condition can be caused by an intake manifold vacuum leak, a bad MAF sensor, a leak in the exhaust system before the front 02 sensor, or a bad front 02 sensor. Usually an 02 sensor code is set if the 02 sensor is bad.
If the motor is a 6 or 8 cylinder motor you would get lean codes for both Bank 1 and Bank 2 if you had a vacuum leak or bad MAF senor. You can still have a Bank 1 lean code if the exhaust coming off of the bank 1 cylinder head has a hole before the bank 1 sensor 1 02 sensor. It won't be a bad MAF sensor or an intake manifold leak because the MAF sensor or intake manifold vacuum leak would make both Banks lean and set codes for both Bank 1 and Bank 2.
Grandpa Jack:
It's not because of ethanol in gas. Just about any regular unleaded gas you'd buy at any gas station in the USA has 10% ethanol in it whether it's labeled as such and besides which, your engine is perfectly capable of running properly over its entire lifespan on a 10% ethanol blend anyway. Don't waste your money trying to find some non-ethanol premium fuel somewhere (if you can even find that in your area) hoping it will cure the problem because it won't. Good luck.
Old Man Dirt:
The first thing to do is find out if the sensor is right!
Lean burn spark plugs look different from "normal" or "rich" fuel mixtures.
If there is a lean burn then it can be a vacuum leak, low fuel pressure or dirty injectors. Low fuel pressure can be the result of a stuck fuel return valve, a fuel filter that needs replaced or a bad fuel pump.
Because the manifold vacuum operates the power brake booster, the problem might be in the brakes.
This error code can also be caused by a bad gasket or crack in the exhaust manifold. If this is the case, fuel mileage will have dropped off and the plugs will show a rich burn.
So pull the spark plugs and see what condition they are in and go from there. https://www.ngksparkplugs.com/about-ngk/…
Steve S:
leaky inlet manifold gasket can cause it any other symptoms like down on power , drinking fuel idling rough?
I doubt it unless you car doesn't like to run on ethanol then I'd assume it would be lean on both banks, try fill up with your regular fuel and throw some injector cleaner in the tank
L.N.:
!0% ethanol is the standard blend and all vehicles should be able to run on it. In 2001 new vehicles were updated to run on up to 15% ethanol though it is much less commonly available.

Leave a Reply