Unsolvable P0171 'System Too Lean' Code

(edit: this ended up having nothing to do with my MAF sensor, it's on ongoing issue that the Toyota service department can't seem to figure out)

Hey guys, sorry if this has been done to death, I did search and found a lot of useful info. However, I've never cleaned my MAF sensor before and am relatively new to DIY vehicle projects.

Yesterday I got a P0171 "System Too Lean Bank 1" check engine light. I posted it in another thread of mine and got a great deal of useful info, primarily that I should clean the MAF myself since it's an easy thing to do and it might solve the issue I'm having.

I found a useful thread on locating and removing the MAF sensor but it was for 2nd gen Tacomas, I have an '04. Also, my truck is supercharged...will that or any of it's components be in the way of me getting to the MAF sensor?

 

Unplug it, remove two philips screws, clean the bulb as well as inside the holes (but don't stick the straw into the holes, the MAF sensor part is inside and is delicate). Reverse the process. Bam.

 

Cool thank you! I searched a little deeper and found this write-up for 4runners of the same generation...

http://4runners.org/writeups/throttle/index.html

Seems easy enough, and it doesn't look like the supercharger will be in the way of getting to it since it's not near the intake manifold. I'll give it a go and report back

 

I just had the same code, I cleaned it and everything is fine now. Did you ever notice if you lost a lot of mpg? Seemed like I could watch my gas guage drop and I was always filling up my tank. Seems to be fine now that I cleaned it?

 

On the contrary, I was actually getting great MPG right before the check engine light came on. I had just completed a 90% highway road trip and got just under 21mpg (good esp considering I have a supercharger). I filled up that night when I got home and the next day I got the code. MPG seems to be normal after cleaning the MAF sensor, that was 5 days ago now and so far so good....no more check engine light.

I did read on here though that if you reset your check engine light by disconnecting your battery, it can take several hours of driving before the ECU can detect the code again, so hopefully I'm still good. Did you disconnect your battery to clear the CEL or did it go away on its own?

 

I just did this not too long ago and used this video. Nice clean instructions, but just remember to put everything back right.

Edit: seems like you already did it. I'm late to the party.

 

Ya I had my buddy clean the sensor and that was about a week ago the light was gone right away and hasn't come back on. MPG is a huge improvement already so I'm guessing I'm good.

 

huh, my light stayed on but I was told I may have to reset it by disconnecting the battery so I did. It's stayed off for 5 days now so hopefully I'm good. Glad to hear you solved yours!

 

Thanks! I actually ended up cleaning it using a video I saw of a guy cleaning one on his FJ cruiser. It was a super easy process, so easy I'm a little embarrassed to admit I was about ready to take it to the dealer to have them do it. As simple as unscrewing the MAF sensor, spraying it, and screwing it back in. I plan on doing it every time I change out my air filter as basic maintenance.

 

Most things mechanically seem pretty intimidating to me until I look them up. Then I see how easy it is to work on our trucks. Still learning more everyday and love it.

 

True that. 10 years ago when I had my first Tacoma, I worked on it all the time; changed out my own brakes, cleaned the TB, even installed a rear diff locker with the help of a friend. Fast forward 10 years later after owning commuter cars and never working on them myself, I feel like I've forgotten everything lol. But it feels good to get back into it. I just prefer that I work on my truck when I want to, not because I have to lol

 

Just FYI,you can reset as well by pulling the EFI fuse from the box under the hood for a couple min. I like this method so that I don't reset everything else in the truck...clock, radio, etc

Also a good anti theft if parking somewhere long term

 

Damn, wish I had known this a couple months ago, would've saved me hundreds on the dealer-installed alarm I bought

Good to know though, thanks!

 

I had the same code for a while. I'd clean my MAF and then next month same problem. Eventually replaced the MAF cus you really shouldn't be relying on cleaning it regularly.

 

When you replaced your MAF the code stopped popping up?

Just curious in case mine resurfaces again.

 

well... I cleaned my MAF for 2 years about once every 3-5 months and then once every month. Then I started misfiring. That is when I replaced the MAF with a Denso oem one. No misfires or lean codes since. Been nearly 2 years now.

 

Good to know, thanks!

 

haha lol... ohh no, sorry to laugh at ya. that sure sucks though you had to drop a bunch of coin on a free mod.

 

lol the actual alarm does have it's benefits (shuts off the ECU if it gets hotwired) also they alarm company pays out a % if the truck gets stolen. But the likelihood of those things happening are pretty slim so this free mod may have been the better option...

 

Very true there are additional benefits to the alarm...