Buick regal 2003 supercharged

Question

2003 Buick regal supercharged has code P0171 but only has condition on one bank how do i know if its an ignition misfire or a defective oxygen sensor and last a fuel injector problem

Answer 1

P0171 Fuel trim lean Bank 1

If a lean condition was caused by a misfire you would code a P0300 or that cyclinder that is creating the misfire, same as with a fuel injector. Check the intake manifold on the side for any coolant leakage that may be entering the intake . Most lean condition are cause by vacuum leaks , vacuum leaks should be check .

 

 Here is a vacuum leak that was causing a P0171, it can be heard but was not seen. looking around the vacuum hose. and inspecting for bloated vacuum lines the leak was found