The code is P0171 System Too Lean (Bank 1). The only symptom I notice is related to the idle speed, and again it only happens when it is really cold. Even without the code, when it is really cold, and I have been driving at highway speed for 20+ minutes (which I do on my daily commute) when I come to a stop, the idle speed suddenly drops to 500.. The common symptoms of code P0171 in a Subaru include rough idling, poor acceleration, increased fuel consumption, and a possible Check Engine Light. 2. What are the possible causes of OBDII code P0171 in a Subaru? Common causes of code P0171 in a Subaru include a vacuum leak, faulty oxygen sensor, dirty or clogged fuel injectors, a.
The P0171 code indicates a lean fuel mixture in the engine's bank 1, which can cause reduced power, rough idling, and hesitation during acceleration. Common causes of the P0171 code include vacuum leaks, faulty oxygen sensors, clogged fuel filters, and malfunctioning mass airflow sensors or fuel injectors.. One of the most common trouble codes with the Subaru Forester is P0171. It indicates that your Subaru Forester is running lean on the bank one side. It's the most common air/fuel mixture-related code. It's not the most complicated OBDII trouble code to diagnose. It is also one of the most common codes. Vacuum leaks