I have several questions concerning the p0171 code concerning "Running lean-Bank 1".

Question

I recently purchased a 2012 Mazda Speed3 with a CAI And blow off valve at the turbo. It also has a Cobb tune. My questions are 1. When the CEL - p0171 code appears, does it put the car in "limp" mode? What I am trying to say, will it inhibit the performance in any way? 2. If the CEL appears with this code, as long as the CEL is on, is the engine having this issue or will the check engine light go away if the engine starts to perform properly again? 3. If the system is indeed running lean for extended periods of time, what are the consequences? What is the worst case scenario?
As I've said, I recently purchased the vehicle from a dealership. I have no information of all the mods that have been done to the car. Who did the mods or when they were installed. The CEL came on after I purchased the car so I would like to see if I can fix the problem before having to drive the couple hundred miles there and back.

Answer 1

P0171 Fuel trim lean Bank 1

The whole purpose of the CK ENG LT is to protect the catalytic convertor and the catalytic is to protect the environment from harmful emission emitted from the vehicle. If the ECM see a fuel trim correction yes the CK ENG LT will turn off, this code should not put the engine into limp mode, Your more than likely looking at a MAF (mass airflow) that is not calculating the correct incoming air, that or a vacuum leak. if there is no vacuum leak you can do a MAF cleaning which is a common cause for a lean fuel trim

Comments

Thanks for the reply Reynaldo. Unfortunately, I had to leave town for work before I could diagnose the problem. In the meantime it has allows to to do a lot of research online relating to this problem. The code appeared while driving in the interstate. I accelerated rapidly and then coasted for a bit when the CEL came on. Since clearing the code I have driven about 200 miles, with quite a bit of aggressive driving on the outskirts of town, and the problem has not reappeared.
Will a generic code scanner allow me to check the fuel trim levels should this code come back and would it be worth investing in one? If the problem reoccurs, I would like to capture data to pinpoint exactly what is going on.