Fault Codes/General Motors Powertrain/651General Motors Powertrain651UnclassifiedGeneralWhat This Code Means651Possible Causes•Mechanical operation issue with the throttle•Programmed governor speeds exceeding 4000 rpm•Very large air leaks below the throttleSuggested Actions1Check the engine for very large air leaks below the throttle2Check the mechanical operation of the throttle3Ensure that any programmed governor speeds do not exceed 4000 rpm4If any other DTCs are present, diagnose those firstRelated General Motors Powertrain Fault CodesDTC 112DTC 122432DTC 416431DTC 422426DTC 423421DTC 424415DTC 434Browse all General Motors Powertrain fault codes→ASK RUDY ABOUT THIS FAULTGet a diagnosis walkthrough for 651 on your specific General Motors Powertrain unit — cited to the OEM manual, not a forum guess.Your question about 651GET THE ANSWERFree account required — we'll bring your question with you.