System running too lean... why???
#1
System running too lean... why???
I know I'm at the wrong forum, but being an owner of a Stang this is the only one I got an account on. My dad's 2003 F-150 4.2 V6 had a service engine soon light come on a few days ago. Thetruck is running completely normal though. I connected it to an OBDII reader and it gave me 2 codes which are p0171 and p0174. The explaination was "system running too lean" and that's for both, bank 1 and bank 2. I first thought it was a bad oxygen sensor, but then why would it be on both banks at the same time? I checked all the vacuum hoses and everything is seems connected right with no leaks or cracks anywhere (the truck has 54k miles on it). I know it can also be caused by a loss of fuel pressure and a faulty MAF sensor which I have not yet tested. I took off the MAF sensor to make sure there's nothing stuck inside and I didn't see a thing. Where should I start or what else could it be? How do I test a MAF sensor? What do I hook up a fuel pressure gauge to? How do I test the O2 sensors without making holes in the wiring to check the voltage? This is driving me nuts, any help is highly appreciated.
#3
RE: System running too lean... why???
Check your PVC hose. I have a ranger edge 4.0Lthat had the same issue that you are describing. I the issue was a cracked PVC hose. It can also be a disconnected vacum line.
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