Information for Code p0171

Engine control computers need to have a specific ratio of air to fuel in order to work properly, and if there is too much of one or the other then it will set a code.

There are several very common things that cause this code:

Dirty Mass Airflow Sensor
Vacuum Leak
Bad Oxygen Sensor(s)
Running Out of Gas

Some other things that can cause this code:

Clogged Fuel Injectors
Leaking Exhaust System
Evaporative Emissions System Malfunction
EGR System Malfuncion

The first thing that I would do is make sure no one has ran out of gas in the vehicle recently. This will cause this code almost every time. The next thing is to clean the MAF sensor. You can buy cleaner specifically for this procedure at any good auto parts store. If you decide to clean the MAF yourself you need to be very careful as it is very fragile. There is a small wire that you will be cleaning that is very easy to break. It is best to use just the aerosol mass airflow sensor cleaner as using a q-tip or something like that can leave debris on it and cause it to not read correctly.

Then you should check for vacuum leaks, especially ones that are after the MAF like tears in the tube that goes from the airbox to the engine. If this is torn it will let air in that the computer cannot tell is coming into the engine.

The next most common cause is bad Oxygen sensors. If they are not working properly then they will not be reading the amount of oxygen in the exhaust gas.

These are the easier things to check. If none of this fixes it then it would be a good idea to take your car to a professional.

Leave p0171 and go to OBD Codes

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