Fault Codes/Discovery Energy, LLC (Rehlko)/P2178Discovery Energy, LLC (Rehlko)P2178ErrorGeneralWhat This Code MeansSystem Too Rich Off IdlePossible Causes•Problem with the closed-loop feedback controlSuggested Actions1Check for misfires2Check fuel quality3Check fuel pressure regulator and outlet pressure4Check for exhaust leaks5Check for intake manifold leaks6Troubleshoot the HEGO sensor for bad leads. Refer to the Heated Exhaust Gas Oxygen (HEGO) Sensor Troubleshooting section7Replace the HEGO sensor. Refer to the Heated Exhaust Gas Oxygen Sensor (HEGO) sectionRelated Discovery Energy, LLC (Rehlko) Fault CodesP2187P2188P2177P2191P2135P2192P2119P2243P2113P2305P2111P2306Browse all Discovery Energy, LLC (Rehlko) fault codes→ASK RUDY ABOUT THIS FAULTGet a diagnosis walkthrough for P2178 on your specific Discovery Energy, LLC (Rehlko) unit — cited to the OEM manual, not a forum guess.Your question about P2178GET THE ANSWERFree account required — we'll bring your question with you.