When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So... I was having lean codes on my truck 09 Ford F-150 FX4 5.4L engine. I changed out my injectors & spark plugs and now im getting rich codes P0175 & P0172. I've changed out 02 sensors recently too. I know I installed the proper injectors and spark plugs so does anyone have any idea what could be going on? Im pretty sure my MAF is working properly as well. It's reading in lb/min. Any help would be appreciated! Thanks in advance.
Last edited by Untamed Element; Mar 9, 2022 at 12:24 AM.
Thanks Jimboy, I'll have to see what the MAF is reading with the engine off. I actually watched this video yesterday but I'm really not sure what my issue is.
Woah!!! Both your short term fuel trims are reading 99.2% your truck is dumping fuel in. Should be +/- 5% or so. I'm surprised your downstream O2 sensors are only reading 0.92 and 0.94 volts for rich. You may want to start with a KAM reset procedure just in case the truck needs a hard reboot.
Woah!!! Both your short term fuel trims are reading 99.2% your truck is dumping fuel in. Should be +/- 5% or so. I'm surprised your downstream O2 sensors are only reading 0.92 and 0.94 volts for rich. You may want to start with a KAM reset procedure just in case the truck needs a hard reboot.
Aka_Ticky yeah! That's ridiculously high! I'm not even sure what a KAM reset procedure is lol but I have a buddy that's a good mechanic so we're going to look at it today and see if we can figure something out. I'll do some research on that procedure though. Thanks!
You can ignore that 99.2%. That is a pcm default value given to scan tool that info is not available ( maybe it is on newer systems) my 2010 5.4 gives same 99.2% and "N/A" on the SHRTFTB1S2. If you want the correct info that provides feedback to the PCM for making corrections to the fuel injectors you need to pull up the STFTB1 & STFTB2 (sensor1 not the S2 sensors) - These fuel trim values will move around from your new upstream O2 sensors output (that are sensing a rich condition in your truck from data you provided ) and will ultimately adjust the LTFT that should read around 0% to be perfect. None are for example my 5.4 runs at -7% at idle.
If your cel is on and you have rich codes you might find the LTFT around -20% or maybe more. I would start your diagnosis from there otherwise you will be chasing ur tail-
Getting codes P0175 & p0172
