Skip the auto shop - Our mechanics make house calls

Q: P0171 and P0174 codes

asked by on

My check engine light came on for bank 1 and 2 upstream o2 sensors. I smell raw fuel from engine compartment, and my fuel tank crushed itself causing a hole in the tank. All this occurred after I replacement my fuel cap when the light came on for faulty cap. I've read the vapor canister purge solenoid is the culprit. Is there any truth to that?

For one, these codes are for a lean condition and are not O2 sensor specific codes. It is true that some of the newer Fords have an issue with the purge valve staying on, putting a vacuum on the system that causes the gas tank to collapse. In fact, there is even a technical service bulletin (TSB) regarding this issue, but it does not apply to your vehicle. One thing I would look at first, is the mass air flow (MAF) sensor. There is a TSB 98-23-03 regarding the codes you have setting as a result of a faulty MAF. Of course, Code P0171 and P0174 can be set by anything that causes a lean condition; from a vacuum leak to a faulty fuel pump. To know for certain, I suggest you have a professional, such as one from YourMechanic, diagnose and repair your vehicle firsthand (https://www.yourmechanic.com/services/check-engine-light-is-on-inspection).

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. P0171 and P0174 codes

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

Q: How do you lock or unlock the seat belts?

Your car is equipped with combination lap and shoulder belts for every seating position (two in the front and three in the rear). While each seat has its own belt, they all work the same way. Here’s how to lock...

Q: Hello, I have a 1997 Nissan Maxima and it has no compression reading from cylinder #2.

Hello. It is possible that you have a bent valve but instead you may have a warped valve seat. Whether or not that is the case what is most likely causing the lack of compression in your engine is a...

Q: Engine problems.

Hello. From what you describe it would appear likely that the backfiring and performance issues are a result of the fuel problem. A rich fuel mixture can be caused by a wide variety of issues. A few things I would...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.