ok so this problem popped up on my car today well its been raining since last night i've had zero problems with all my mods(check my profile for my list of mods) and zero problem codes until today

so i went to advanced auto parts (have a mental health day, due to rain i don't work in the rain) and they ran the code and popped up with the code "Code P0171 (system too lean - bank 1)"

my idle was perfect, vacuum was a was down a couple of hairs, car ran perfect...

the parts guy said it could be the O2 sensor? but idk so when i got home i readjusted my Eco-Tek CB-26P <link and pulled my EFI fuse out that cleared the code

looks like i might have to try too clean the MAF sensor next when it quits raining :?

 

that code normally means oxygen sensor isn't working efficiently. or possibly the fuel injection system is clogged.
Often it's just a faulty or hyper-sensitive sensor. Has your gas mileage gone down? if not , you might not need to do anything. O2 sensor is an expensive repair and may be a waste of money if you don't really need it. On my Echo I was getting that same code and I ignored it for 100,000 miles with no problems. eventually the light stopped coming on, possibly because it burnt out. I kept an eye on my gas mileage and it reamined over 40.

 

i cleaned the MAF sensor and reset the code by removing the EFI fuse so far so good and ifs its the O2 sensor that'll be easy too fix just $$$ to buy :?

 

if it was the o2 sensor not working it would burn rich, do you use a faulty plug on the headers, it could be in a bad position. just a thought.

 

i drive a xA, no O2 sensor in the header only in the down pipe before and after cat

and my CEL hasn't returned yet!