Skip the auto shop - Our mechanics make house calls

Q: My check engine light is on reading code po171 lean

asked by on

My check engine light is on reading a code of po171 lean. Sometimes when I accelerate it hesitates like if your riding a horse or in a boat swaying front to back but this rarely happens but it still happens. I also have some kind of fluid I believe to be oil coming down and covering the bottom of my engine. No other problems besides lack of alot of power when accelerating and that oil on the bottom. I also just replaced the mass flow sensor and got an oil change. Any thoughts?

My car has 171000 miles.
My car has an automatic transmission.

The code P0171 is for the engine control module is getting an O2 sensor lean bank 1 problem in the engine and has tried to compensate by making the injection system go rich on that bank. There is a long list of possible causes like intake bolts loose, injectors sticking, vacuum leaks, clogged injectors, carbon buildup on injectors or valves. The list goes on. You will need to have the pinpoint test performed to diagnose the problem and code to see if there is a sensor issue or a problem with another engine component. The oil leaking may have got on the O2 sensor and caused a bad reading. If this is the case, then the oil leak and O2 sensor will need to be repaired. I recommend having a mechanic come to your home or office to give the Check Engine Light a thorough inspection to ensure appropriate repairs are made.

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

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: Cracked bushings

Hi. The vehicle is equipped with many suspension components that involve rubber bushings for comfort and noise dampening. Dry-rot or large cracks in these bushings are signs of age and wear and must be corrected to avoid problems from noise...

Q: Car is running slow, what could it be?

If you already replaced the sensor then now it will need that connector you've mentioned. Replacing it may fix the code P0502. The code P1406 is for the EGR valve position, you would need to have the valve tested to...

Q: Car normally runs great. I changed the MAP and it still shuts off at stop lights or when in drives through lights.

Hello. The first task is to retrieve the problem codes which are setting the Check Engine light. The stalling at intersections may be a dirty or malfunctioning idle air control valve, throttle body, or dirty fuel injectors. Certainly, the bad...

Related articles

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...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.