Engine Code P0171

[cbwtaco]

My 1999 Tacoma has an engine code P0171.
I read bobdotson's messge regarding the oxygen sensor.
Is there any info available for further troubleshooting this code?

[aimdas]

Do you have an aftermarket intake by any chance? That code is "P0171 - Bank 1 Lean". If you have an aftermarket intake then you're fuel pump can't keep up with the extra air and it's making you run lean.

[cbwtaco]

Aimdas - Thanks for your reply, the intake is stock however I was told that some of the exhaust is not stock (no headers, the muffler was changed by the previous owner and I had a "more stock type muffler" put back on) I believe that the catalitic converter is stock. Any ideas on where I would go to trouble shoot this code?

[aimdas]

It's prolly your mass air flow sensor. Could either be dirty, or need to be replaced. Here's a link to another board I visit that talks about this problem. It's a group of thousands of tacomas nationwide.

http://forums.delphiforums.com/tacom...es?msg=95238.1

[cbwtaco]

Thanks for your help! I wil check out the site!

[whammermail]

Originally Posted by aimdas

It's prolly your mass air flow sensor. Could either be dirty, or need to be replaced. Here's a link to another board I visit that talks about this problem. It's a group of thousands of tacomas nationwide.

http://forums.delphiforums.com/tacom...es?msg=95238.1

I had the same code turn up a few months ago. I was told it could be a bad injector (ouch) after the fuel pressure checked out ok, but decided to clean the Mass Air Flow sensor after reading some of the threads related to this code. I just removed the MAS and sprayed it off with non-residue electrical parts cleaner and unhooked the battery to reset the light. Did this a week ago and the light is still off, truck running great. Id like to know if anyone else with this problem is currently using or has used an aftermarket air filter. I used to have a K&N Filtercharger which I removed and replaced with the stock air box and a K&N filter. Since cleaning the sensor I put a paper filter back in. Don't know if the problem was related to the aftermarket filters or not. Thanks for any input on this.