Common Causes of The Code P0171 and How to Clear it via Launch Creader V+
You recently had an oil change done or you replaced the air filter, when you’re driving, your check engine light came on but nothing feels different. The check engine code say P0171 Low Fuel Trim. This article will point out some of the common causes of the code P0171: leaks in the intake system that throw off the mass airflow sensor.
When you use scan tool Launch to diagnostic and say P0171, which is means Low Fuel Trim. Open your hood and look for where the air box is.
Look around the air box see if there’s anything loose.
There happens to be a mass airflow sensor right here
See if this snorkels loose
After checking, everything looks good.
Pull the engine cover off so that we could see a little bit better underneath. After take pull the cover off, now you can see where the throttle body is and see where snorkel goes into the throttle body. We found a hose loose.
Now why this hose is loose and not where it should be, they probably took the snorkel off when replacing the air filter or if you did it at your house you forgot to hook the tube back up. Slide the tube back in position, make sure all these are tight that should be good.
After tight everything, we should be able to clear the code and be on our way.
The reason way we got this code and just a little simple hose being popped off like this could cause that code is because of the mass airflow sensor. The mass airflow sensor senses air going into the engine and if any air is coming into the engine that didn’t go past that sensor that’s going to cause a code. If you had one of these low fuel trim codes and you didn’t find anything near the air box or the mass airflow sensor, definitely check any of these other hoses. Make sure none of these are loose or you don’t hear any air you could start the engine and listen for a whistle in that area that might help you find a leak.