P0174 main code and secondary code P0171

Hi guys, my Grand Marquis LS 98 just got the Check Engine light, few minutes ago, that came up after a warning from the car when it got 14 liters (3.7 gallons) and economy said you have 80km (50 miles) only for the remaining fuel and I push my pedal gas, I don't know if this acceleration means something, but the car still has power, I mean nothing different on the car, only the check engine light turned on. Any ideas why this happened? Thanks

Sorry it is in Spanish, lol!