I keep getting OBD-II codes P0171 and P0174 2004 v8-5.4l ...

Q: I keep getting OBD-II codes P0171 and P0174

asked by on November 04, 2016

I keep getting the P0171 and P0174 lean bank 1 and 2 code. When I fogged the intake the only smoke came from the press cap on the idle air control valve, I did this on my 02 F-150 with a 5.4 no smoke. When I say press cap I mean the cap on he valve that looks like a freeze plug crimped over the valve. Is this normal, since taping around the valve I haven't had the check engine light for over 300 miles.

My car has 203500 miles.
My car has an automatic transmission.

Since you have codes that both banks are lean then the problem will most likely be from air entering the intake manifold after the mass air sensor. The idle air control valve should not have any air leaks from the valve and may be contributing to the codes you are getting. It would be recommended to scan the computer data to see if the mass air sensor is registering the correct barometric pressure reading. This reading should show the proper pressure for the altitude your vehicle is at. If the data is reading that you are above more than 1000 feet more than what you are at then the mass air sensor is causing the codes and the mass air sensor needs replaced. The mass air sensor can be damaged by an air filter that is the oil bath type and should be the dry type filter. Replace the air filter if it is incorrect type or is dirty restricting air flow into the engine.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Clutch wont disengage 1993 Ford Ranger

Hello - first off, yes, the clutch disc "spring side" faces the pressure plate. Second - several problem could be causing the clutch to fail to disengage. A frozen, or failing pilot bearing can cause the same symptom as a...

Gear selector stuck in park

Hello. This is a common problem in both Chevrolet and GMC trucks and SUVs of that year. The safety system requires pushing on the brake to start the vehicle, so the problem is likely that the brake switch on the...

Gear shift indicator won't go into park

Hello, thanks for writing in. There is an adjustment procedure for the shift indicator on your vehicle. Some shop repair manuals will outline how to make the adjustments, but it would be best to consult a certified mechanic that has...

Related articles

A Buyer’s Guide to the 2012 Ford Mustang
The The Ford Mustang has been an iconic vehicle for half a century, and its latest styling and updates only make it more attractive and more popular with American drivers. While its exterior may not be quite as eye-catching as...
The Best Used Cars to Buy If You're a Carpenter
If If you're a carpenter, and working for someone else, the best used car is whatever you like that gets you to work on time and holds your tools – in short, practically any used car will do. If you...
The Best Used Cars to Buy For a Graduation Gift
Your Your little bundle of joy has grown up and on the cusp of entering adulthood. Graduating is a milestone, and you want to reward their hard work and show how proud you are. Buying a used car is a...