Skip the auto shop - Our mechanics make house calls

Q: Error code P0171 and P0174

asked by on

I used the OBD II / EOBD CODE READER and found the following code P0171 System too lean P0174 System too lean Freeze Frame: DTCFRZF P0171, Fuel sys 1 CL, Fuel sys 2 --, Load_PCT (%) 75.29, ECT( ‘C) 78.00, SHRTFT1 (%) 0.00, LONGFT1 (%) 25.00, SHRTFT2 (%) 0.00, LONGFT2 (%) 25.00, MAP (kPa) 47.00, RPM(rpm) 705.50, VSS(km/h) 0.00, SPARKADV 4.5,
IAT(‘C) 00.00, MAF(g/s) 6.28, TP(%) 18.43, I don’t feel anything while driving the 2006 Ford Five hundred SEL, It accelerates well and goes easily to 40miles per hour when given the acceleration (I have not tried beyond 40 miles/hr in order to avoid any damage, as I bought it recently and want to repair it before use) the odometer reads about 200,000 miles, what can be the possible reasons of this errors and what should I do to make it a smooth running vehicle?

A: The high positive long term fuel trim sugge...

The high positive long term fuel trim suggests a vacuum leak and/or inadequate fuel delivery. But there are other causes that have to be evaluated as well: bad oxygen sensor(s); dirty MAF sensor; stuck open EGR valve; weak fuel pump; restricted fuel filter; leaky fuel pressure regulator; dirty fuel injectors; and exhaust restrictions such as a clogged catalytic converter. In addition on Ford models, a well known issue is that P0171 and P0174 lean codes can occur if the EGR differential pressure sensor goes bad. After 6 years or 60,000, that sensor is reported to have a high failure rate. If you desire that your vehicle's lean operating condition be diagnosed and corrected YourMechanic can dispatch a certified Mechanic to your home or office and perform a mobile diagnostic and repair. Please let us know if you have additional questions or concerns.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Truck stalling 1991 Ford F250

Hi there - I suspect you're correct as to this being a fuel system issue. I would flush the tank, replace the fuel filter, fill with fresh fuel, then cycle the fuel pump before attempting to start the engine. You...

Q: Error codes P0171 and P0374

Hello. These issues can be caused by a few things. From the codes it sounds like there may be an issue with the fuel system. It may also be an issue with the air intake system allowing too much air...

Q: went into failsafe can this be cleared by me

Hi there. This problem is very common after replacing engines on modern vehicles. The ECU needs to be reset by a Ford dealership in order to fix this issue.

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
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.