System Too Lean (Bank 1)

What does this mean?

Code P0171 indicates the engine control module has detected that the fuel system on Bank 1 is running too lean — there is too much air or too little fuel in the air-fuel mixture. The long-term fuel trim has exceeded its adjustment range.

Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Kia Optima models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.