A P0171 code indicates a lean air-fuel mixture on Bank 1, typically caused by too much air, not enough fuel, or a faulty sensor. For off-road equipment, common culprits include intake leaks, dirty MAF sensors, fuel delivery problems, or O2 sensor issues. Symptoms range from rough idle and hesitation to power loss under load. This guide provides a systematic diagnostic approach—check the intake system first, then the MAF sensor, fuel supply, and finally the O2 sensor—helping operators avoid unnecessary part replacements and get equipment back to work efficiently.