Decoding Engine Code P0171 The Ultimate Troubleshooting Resource

Code P0171 indicates Bank 1 of the engine has a lean fuel mixture. P0174 indicates Bank 2 of the engine has a lean fuel mixture. This code is triggered by the first downstream (front) O2 sensor. The sensor provides a reading of the air:fuel ratio leaving the engine's cylinders, and the ... The most common cause that we see at the dealer is a MAF sensor, especially if you have a K&N or other oiled air filter. O2 sensors can also ... My 2005 mustang GT's check engine light came on yesterday. The 2 codes were P0171 and P0174 which are lean codes for bank 1 and 2 of the ... A quick search says possible causes dirty air filter, intake leak, mass airflow sensor, or oxygen sensor, among other things. More often than not P0100, P0110 and P0171 are related to the MAF being dirty or worst case damaged. Normally you start with the lower codes ... The engine seems to be running really rich (can smell a lot of gas at startup). I've checked for exhaust leaks, did my best to check for a vacuum leak, and ... P0171 is a code indicating that the engine is experiencing a leaner fuel mixture than what's commanded (too much air or not enough gasoline). It could be lean under high load/demand conditions and fine at low load. Mixture lean/rich codes can't set until the O2 sensors are active and ... I was able to get enough gas to get to a decent gas station to fill the tank. On my way home I got a check engine light and the code was P0171( ...