Fault Codes/Discovery Energy, LLC (Rehlko)/P1521Discovery Energy, LLC (Rehlko)P1521ErrorFuelWhat This Code MeansThrottle Zero Cycle Rest Value IncorrectPossible Causes•Bad throttle body or leadsSuggested Actions1Troubleshoot the TP sensor leads. Refer to the Throttle Position (TP) Sensor Troubleshooting section.2Replace the throttle body. Refer to the Air - Fuel Mixer, Adapter, and Throttle Body Assembly section.Related Discovery Energy, LLC (Rehlko) Fault CodesP1522P1562P1520P1633P1134P2112P0224P2163P0223P2164P0222P2172Browse all Discovery Energy, LLC (Rehlko) fault codes→ASK RUDY ABOUT THIS FAULTGet a diagnosis walkthrough for P1521 on your specific Discovery Energy, LLC (Rehlko) unit — cited to the OEM manual, not a forum guess.Your question about P1521GET THE ANSWERFree account required — we'll bring your question with you.