Ok so you have got your OBD2 scan tool and now you can see what is happening with your car. The check engine light now comes on. You plug in your tool and you get an error code. What now? What do these codes mean? In this article, we explore the list of OBD2 codes you might encounter while using OBD2 tools.
Depending on the OBD2 scanner you are using, it may link automatically to the page for this code and tell you what to do. If not, we will cover a common OBD2 code below.
Code P0171 (“system too lean bank 1”) means that the computer has noticed, by reading the oxygen sensors, that there is too much air going into bank one (the bank that includes cylinder number one in the firing order in v style engines).
This information also applies to code P0174 (“system too lean bank 2”) as this code is the same except for the opposite bank of cylinders.
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.
What Causes a P0171 Code?
- Dirty Mass Airflow Sensor
- Vacuum Leak
- Bad Oxygen Sensor(s)
- Low Fuel Pressure
- Running Out of Gas
Less Common Causes
- Clogged Fuel Injectors
- Leaking Exhaust System
- Evaporative Emissions System Malfunction
- EGR System Malfunction
How to Fix Code P0171
1. Check Gas Level
The first thing that I would do is make sure you have not run out of gas in the vehicle recently. This will cause the P0171 code to appear almost every time.
2. Clean MAF Sensor
If you decide to clean the MAF yourself, then you need to be very careful as it is very fragile. There is a small wire you clean that is very easy to break. It is best to use just the aerosol mass airflow sensor cleaner than using a Q-Tip. Something like the latter can leave debris on it and cause it to not read correctly.
Then you should check for vacuum leaks, especially the ones that are after the MAF. Note that tears in the tube that goes from the air box to the engine. If you tear this, it will let air in and the computer cannot tell what is coming into the engine.
3. Check Oxygen Sensors
The next most common cause for this code code is bad oxygen sensors. If they are not working properly, then they will not be reading the amount of oxygen in the exhaust gas.
4. Check Fuel Pressure
Another common cause of this code is low fuel pressure. If the fuel pump does not put the right pressure of fuel into the fuel system, then the result can be this OBD code.
If you want to check it, you will need to have a fuel pressure tester that will fit your fuel system. Then you just need to check the pressure. If it is low, you need to replace the fuel filter first (unless if you have done recently it). After you have changed the fuel filter, you need to check the fuel pressure again. If it is still low, then you most likely have a fuel pump problem.
These are the easier things to check with code P0171. If none of this fixes it then it would be a good idea to take your car to a professional.
Please note this information is from a great website called: http://www.myautorepairadvice.com/obd_2_codes.html
If you need more information on OBD2 Codes List and what are the faults that could appear, we highly recommend that you check this website out.