Can dirty fuel injectors cause a "lean" fuel mixture?


#1

Check engine light came on after a day of routine maintenance. Scan says lean fuel, P0171 at advance auto parts. Tightened all bolts, hoses etc. After clearing code it comes back on after 15 miles of driving…could it be dirty fuel injectors?? Any thoughts?


#2

Gasoline contains detergent to prevent dirty fuel injectors. Fuel filters are also there to prevent dirty injectors. Most of the adds you see for fuel injector cleaners are just trying to sell something you don’t normally need, and most injector cleaners are just about worthless.

You don’t specify make, model, year, or mileage, so it’s difficult to say, but I’d suspect the O2 sensor before the injectors.


#3

Check for any vacuum lines being dislodged.
Dirty fuel injectors should not cause a lean reading but could cause a rich reading.
Dirty injector = less fuel = misfire = too rich basically.


#4

Gasoline contains detergent to prevent dirty fuel injectors.

This will HELP, but won’t do it completely.

Fuel filters are also there to prevent dirty injectors.

And if the filter isn’t changed too often the dirt can get through. Every time I change the filter on my Pathfinder or wifes Accord…the filter is FILTHY…and I change the filter far sooner then what the manual changes.

IF you change your filter before it gets too clogged then it SHOULD keep the injectors clean. But since there’s a problem…I suggest running a couple bottles of Chevron Techron or Seafoam through. If there is dirt this should clean it out. Just follow directions.


#5

I have nothing against Techron, which I use once or twice a year myself, but I still think most fuel injector cleaners are not worth the money, and really won’t clean anything.


#6

IF you have a dirty injector, BG 44K WILL clean it. Available at Car-Quest and NAPA stores or online. Chevron Techron works pretty good too.

And yes, a dirty injector can cause a lean condition. But CEL’s lie a lot…A vacuum leak is a more likely cause…


#7

Another condition that can cause a “bank lean” error is a contaminated MAF sensor. I had a lean code come up before, possibly the same one, that returned after clearing it. A thorough cleaning of the MAF sensor with some electronics cleaner(available at you auto parts store) solved that issue. 4+ yrs now and it hasn’t come back


#8

You really need a good mechanic to check it out. The purpose of the Electronic Control Module (ECM) is to maintain emissions stability as conditions vary. The computer (ECM) will often react to a condition in one direction by over-compensating, thus showing a fault that is the opposite of the cause. So a leaking injector can cause a rich cylinder. The exhaust sensor (O2 sensor) “sees” rich, so the computer leans the mix out. The exhaust is still rich so more lean, etc. finally resulting in a lean exhaust signal as the computer goes nuts trying to compensate for that lean cylinder. There are many other ways untrained mechanics are fooled by the computer.

I have driven an '89 Olds Calais, '93 GrandAM, '96 TransAm and '01 GrandPrix each in excess of 150,000 miles. I’ve never had “dirty injector” problems, never used any injector cleaner and never paid to have the injectors “cleaned”. Modern fuels contain sufficient additives to prevent problems, and cleaners can cause long term damage to fuel systems. Note the warnings on the back of the bottles about dilution and frequency of use, and the absence of any such recommendations in your owners manual. That should tell you something.


#9

I have nothing against Techron, which I use once or twice a year myself, but I still think most fuel injector cleaners are not worth the money, and really won’t clean anything.

I agree with that completely…But that’s ONLY if the car has been maintained properly. Someone who neglected ever changing the fuel filter may need it.