System Too Lean (Bank 1)
The engine computer has detected that bank 1 is running lean, which means the air-fuel mixture has too much air or not enough fuel. This can cause rough running, poor fuel economy, hesitation, or a check engine light. The most common causes are vacuum leaks, a dirty mass air flow sensor, or a fuel delivery problem.
You can usually drive short distances, but the engine may run poorly and fuel economy may drop. If the engine misfires, stalls, or runs very rough, stop driving and repair it soon.
P0171 means the powertrain control module has detected a lean air-fuel condition on bank 1. The fuel trim values have reached a limit trying to correct the mixture, usually because of unmetered air entering the engine, incorrect airflow readings, or insufficient fuel delivery. The fault may be caused by a vacuum leak, contaminated MAF sensor, low fuel pressure, restricted fuel filter, weak pump, dirty injectors, or outdated control module software.
It means bank 1 is running too lean, so the engine is getting too much air or not enough fuel.
Yes. Vacuum leaks are one of the most common causes of this code.
Yes. If the MAF sensor reads air flow incorrectly, the engine computer may reduce fuel too much.
It may clear temporarily if the condition goes away, but it will usually return if the root problem is still present.