There are 3 stored owner reports matching the engine leading-label group for the 2012 GMC Sierra in our NHTSA-sourced dataset. These are unverified consumer reports and may not reflect confirmed defects.
This group counts stored reports whose component label starts with one of this site's matching prefixes, ignoring case. Each matching report counts once within the group. Components mentioned later in the label or only in the narrative are not searched. How component counts work
Loaded 3 of 3 matching reports.
Open the full vehicle complaint log (all categories)ENGINE WILL INCREASE IDLE FROM 700 TO 900 AT ANY TIME. ONE CAN BE SITTING AT A TRAFFIC LIGHT AND IT MIGHT INCREASE OR DECREASE. I PULL A 5TH WHEEL (35 FEET) AND IT IS VERY DIFFICULT TO STOP WITH THE ENGINE TRYING TO KEEP GOING. ALSO IT IS VERY SCARY TO STOP ON SLIPPERY ROADS. THIS DID NOT START UNTIL THE VEHICLE HAD APPROX. 35,000 MILES ON IT. THE DEALER TELLS ME IT IS NORMAL, BUT I HAVE TALKED TO OWNERS OF THE GM DIESEL FROM MODEL YEAR 2008 THROUGH 2015 AND NONE OF THEM HAVE THIS CONDITION. *TR
THE FUEL INJECTION PUMP CP4 HAD A CATASTROPHIC FAILURE AS I WAS DRIVING ON A HEAVILY TRAVELED FOUR LANE HIGHWAY, US RT.20. I LOST POWER STEERING AND BRAKES. I FELT FORTUNATE THAT I WAS NOT TOWING A 16,000 LB. FIFTH WHEEL CAMPER DOWN A MOUNTAIN ROAD.I SAY THIS BECAUSE IT WAS EXTREMELY DIFFICULT TO MAINTAIN CONTROL OVER THE TRUCK STEERING IT AND BRINGING IT TO A CONTROLLED STOP. I HAVE READ ABOUT THESE PUMPS FAILING ON NUMEROUS DIESEL FORD AND GM TRUCKS. I ALSO FEEL IF A WOMAN OR SMALL PERSON HAD THIS HAPPEN TO THEM THE OUTCOME COULD END IN LOSS OF CONTROL RESULTING IN INJURIES EVEN DEATHS. THE ONLY ONE THAT KNOWS THE ACTUAL NUMBER OF PUMPS THAT HAVE FAILED IS THE MANUFACTURERS, WHO WILL NOT SHARE THAT INFORMATION WILLINGLY. *JS
TL* THE CONTACT OWNS A 2012 GMC SIERRA. THE CONTACT STATED THAT WHENEVER THE VEHICLE WAS IDLING THE CONTACT NOTICED THAT THE VEHICLE WOULD VIBRATE WITHOUT WARNING. THE VEHICLE WAS TAKEN TO THE DEALER WHERE THE CONTACT WAS INFORMED THAT THE FAILURE COULD NOT BE REPAIRED. THE CURRENT AND THE FAILURE MILEAGES WERE 1,200. ..UPDATED 04/16/12 *BF UPDATED 05/07/12
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
NHTSA source checks for this vehicle year
Checks are recorded separately for each dataset, not for the whole page. Dates use UTC. A missing check date does not mean no records exist.
Vehicle import recorded: Apr 28, 2026. This is the stored import date, not confirmation that every source was successfully refreshed.