2008 GMC Yukon Engine Problems

I purchased a MagnaFlow aftermarket catalytic converter system for my 2008 GMC Yukon SLT 5.3L through Walmart’s online marketplace, sold by a third-party vendor called OurDealsRock. The product was advertised as “50-state legal” and compatible with vehicles registered in New York State. However, shortly after installation, my check engine light turned on, and diagnostic codes P0420 and P0430 (Catalyst System Efficiency Below Threshold) appeared. Initially, I thought this was a minor sensor issue, but over time, the vehicle’s performance gradually deteriorated. I noticed reduced acceleration, poor fuel economy, and eventually significant loss of power. The vehicle began shaking under load, misfiring, and overheating. These symptoms worsened steadily—not immediately—but progressively after continued driving with the aftermarket converter installed. I had the vehicle inspected by a certified mechanic, who confirmed that the MagnaFlow converter was not CARB-compliant, was not approved for use in New York, and that it had been illegally marketed as such. He also informed me that prolonged use of a non-compliant, malfunctioning converter caused excessive backpressure, leading to complete engine failure over time. The diagnosis was confirmed by a second mechanic before I committed to the engine replacement. The product was later removed from Walmart’s site, becoming unavailable for sale in my zip code [XXX] ) shortly after my initial complaint. This shows clear acknowledgment that it should never have been sold to a New York consumer in the first place. But by the time it was taken down, the damage had already been done. Component/system that failed: •MagnaFlow aftermarket catalytic converter system •Ultimately caused failure of the vehicle’s engine block Safety concerns: •My family and I were unknowingly driving with a damaged and failing engine •The vehicle’s degraded performance, overheating, and power loss could have compromised our safety during highway d INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Oil leak in Engine in motor problem

Model Year(s):2009Manufacturer:GENERAL MOTORS CORP.Campaign ID Number:09V154000Potential Number of Units Affected:27188Summary:GM IS RECALLING 27,188 MY 2009 CADILLAC ESCALADE, ESCALADE HYBRID, ESCALADE ESV, AND ESCALADE EXT; CHEVROLET AVALANCHE, SUBURBAN, TAHOE, TAHOE HYBRID, AND COLORADO; AND GMC YUKON, YUKON HYBRID, YUKON XL, AND CANYON VEHICLES. THE FUEL SYSTEM CONTROL MODULES MAY HAVE A CONDITION IN WHICH AN ADHESIVE SEPARATION OF THE ROOM TEMPERATURE VULCANIZING (RTV) SEAL BETWEEN THE SEAL AND THE HOUSING MAY ALLOW WATER TO SEEP INTO THE MODULE.Consequence:WATER IN THE MODULE COULD CAUSE A SHORT OR OPEN CIRCUIT, ILLUMINATION OF THE SERVICE ENGINE SOON LAMP, SETTING OF DIAGNOSTIC TROUBLE CODES OR THE ENGINE MAY BE HARD TO START, MAY NOT START OR MAY STALL INCREASING THE RISK OF A CRASH

VEHICLE WILL ABRUPTLY STOP WITHOUT ANY WARNING WHEN STARTING TO ACCELERATE FROM ZERO UP TO ABOUT 10 MPH. ALL ENGINE INDICATOR LIGHTS WILL FLASH INCLUDING AUDIBLE WARNINGS OF MALFUNCTION. I MUST COME TO A COMPLETE STOP, PUT THE VEHICLE IN PARK, THEN PROCEED TO RESTART THE VEHICLE. A REAR END COLLISION IS INEVITABLE.

5.3 SEVERE OIL CONSUMPTION. AFTER DEACTIVATING THE FUEL MANAGEMENT SYSTEM IT DID SLOW THE CONSUMPTION BUT DID NOT ELEMINATE PROBLEM. NO OIL LEAKS ON ENGINE. MECHANIC SAID IT'S BURNING IT. SO HOW IS THE ECO FRIENDLY? I'VE OWED THIS VEHICLE SINCE 150K NOW I'M ABOUT 180K

ENGINE FAILURE AT 64,000 MILES. DROVE VEHICLE FROM HOME AND THEN VEHICLE IMMEDIATELY BEGAN SHAKING VIOLENTLY. TRUCK DRIVING FINE UP UNTIL THAT POINT. NO WARNING SIGNS. NO CHECK ENGINE LIGHT BEFOREHAND. VEHICLE NOW AT GMC DEALERSHIP AND NEEDS NEW ENGINE FOR UP TO $10,000. GMC IS NOT COVERING THE EXPENSE. GAVE $2,000 TOWARDS THE REPAIR. VEHICLE PAST WARRANTY PERIOD. ENGINE SHOULD LAST LONGER THAN 64,000 MILES. REGULARLY MAINTAINED.

DRIVING 45 EXITING THE FREEWAY WHEN WARNING ENGINE LIGHT COME SON " ENGINE POWER REDUCED" AND DROPPED THE CAR TO 1MPH ALMOST CAUSING AN ACCIDENT. I WOULD PRESS ON THE GAS PEDAL AND THERE WAS NO POWER IT HAD ME STALLED ON THE OFF RAMP EXIT DURING BUSY MORNING TRAFFIC. AFTER 10 MINUTES OF BEING STALLED AND ATTEMPTING TO GIVE THE GAS PEDAL IT FINALLY MOVED FOR ME TO GET OVER OUT OF THE WAY. THE ENGINE LIGHT IS STILL ON. VERY DANGEROUS LUCKILY NO ACCIDENT AND I DIDNT HAVE MY KIDS IN THE CAR.

TL*THE CONTACT OWNS A 2008 GMC YUKON DENALI XL. THE CONTACT STATED THAT AFTER A REGULAR INSPECTION BY THE DEALER, THE TECHNICIAN NOTIFIED THE CONTACT THAT THE MOTOR MOUNT WAS RUSTING AND NEEDED TO BE REPLACED. THE MANUFACTURER WAS MADE AWARE OF THE FAILURE. THE FAILURE MILEAGE WAS UNKNOWN.

MY 2008 YUKON XL IS GIVING SEVERAL ERROR MESSAGES. TRACTION CONTROL OFF, SERVICE STABILITRAC, CHECK ENGINE LIGHT REMAINS ON EVEN AFTER I'VE REPLACED THE THROTTLE POSITION SENSOR, COIL PACK, FULL TUNE UP NOTHING SEEMS TO FIX THE ISSUE AND I SEE THAT I'M NOT THE ONLY ONE EXPERIENCING THIS ISSUE. ANY INSIGHT ON RESOLVING THIS PROBLEM WOULD BE GLADLY APPRECIATED IT IS ALSO USING MORE OIL THAN USUAL. *TR

TL* THE CONTACT OWNS A 2008 GMC YUKON HYBRID. THE CONTACT STATED THAT WHILE DRIVING 65 MPH, THE ENGINE STALLED WITHOUT WARNING. THE VEHICLE WAS TAKEN TO THE DEALER FOR INSPECTION AND THEY STATED THAT THEY COULD NOT DUPLICATE THE FAILURE. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS NOT NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS 15,000.

TL* THE CONTACT OWNS A 2008 GMC YUKON. THE CONTACT STATED WHILE DRIVING 35 MPH THE VEHICLE STALLED. WHEN THE CONTACT LOOKED UNDERNEATH THE HOOD, THE CONTACT OBSERVED THAT THE VEHICLE WAS ON FIRE. THE POLICE AND FIRE DEPARTMENT EXTINGUISHED THE FIRE. THE ORIGIN OF THE FIRE WAS UNKNOWN. A POLICE/FIRE REPORT WAS FILED. THERE WERE NO INJURIES. THE INSURANCE COMPANY WAS NOTIFIED AND STATED THE VEHICLE WAS DESTROYED. THE DEALER NOR MANUFACTURER WERE NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS 64,000.

WAS WAITING FOR A RED LIGHT TO CHANGE AND SUDDENLY MY DASHBOARD LIT UP SAYING IT WAS REDUCING POWER TO THE ENGINE, DISABLING STABILITY CONTROL AND SOMETHING ELSE.. I WAS NOT ABLE TO DRIVE THE CAR FOR FOR 2 HOURS AFTER THAT... I.GOT THE CAR TOWED TO MY HOUSE AND WHEN I WENT BACK TO FALLOWING MORNING THE CAR STARTED WITH OUT THE ENGINE LIGHT ON..2 DAYS AFTER THE SAME THING HAPPENED WHILE DRIVING ON THE HIGHWAY AT 65 MPH, IT WAS A SCARY EXPERIENCE SINCE THE CAR REDUCED POWER VERY FAST TO 20 MPH.. ALMOST GOT INTO AN ACCIDENT. *TT

TL* THE CONTACT OWNS A 2008 GMC YUKON DENALI XL. THE CONTACT STATED THAT WHILE DRIVING 55 MPH, THE VEHICLE STALLED AS THE CHECK ENGINE LIGHT ILLUMINATED. THE VEHICLE WAS TAKEN TO THE DEALER FOR INSPECTION WHERE THEY STATED THAT THERE WAS SOMETHING WRONG WITH THE OIL CONSUMPTION. THE VEHICLE WAS REPAIRED BUT THE CONTACT DID NOT KNOW WHAT WAS REPAIRED. THE FAILURE RECURRED AT 60,000 MILES. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS 30,000.

WHILE USING REMOTE START THE VEHICLE MAKES LOUD NOISE AND SHUTS OFF ENGINE. IN ADDITION THERE IS A RATTLING NOISE HEARD IN THE ENGINE. MANUFACTURER HAS ATTEMPTED TO FIX PROBLEM BUT STATES THERE ARE DOZENS OF VEHICLES THAT WERE MADE INCORRECTLY AND THERE IS NO WAY FOR THEM TO FIX THIS ISSUE. *TR

THIS IS IN REGARDS TO GMC BULLETIN #PIP4112J : SAG OR HESITATION ON ACCELERATION (NORMAL OPERATION CHARACTERISTICS) - (JUL 21, 2011). I'VE BEEN HAVING THIS PROBLEM SINCE DAY ONE AND TOOK THE SUV TO MANY DEALERS BUT DEALERS COULD NOT VERIFY THE CONCERN UNTIL NOW. THE 2008 GMC YUKON XL DENALI WOULD STOP ACCELERATING FOR 2-3 SECONDS WHEN THE GAS PEDAL IS PRESSED. MOST OF THE TIME IT IS WHEN I AM TRYING TO PASS A LANE, TRYING TO ENTER HIGHWAY, TRYING TO CLIMB A MILD HILL OR TRYING TO AVOID A POTENTIAL ACCIDENT. AFTER THE DELAY, THE TRANSMISSION WOULD DOWN SHIFT AND I THINK IT DOWN SHIFTS TO EITHER 1ST OR 2ND GEAR CAUSING THE SUV TO ROAR LIKE CRAZY AND SHOOTS OUT LIKE A CANNON. I HAD AN INCIDENT WHERE THE COPS GAVE ME A WARNING WITH THE LIGHTS AND SIREN PROBABLY THINKING THAT I WAS DRIVING RECKLESSLY. THERE WERE ALSO INCIDENTS WHERE I'VE HAD THE GAS PEDAL PRESSED DOWN ABOUT 80%-90% TRYING TO CLIMB A MILD ELEVATION AND EITHER THE ENGINE AND OR TRANSMISSION STARTED TO CHOKE. IT WAS SO BAD THAT THE DENALI ALMOST CAME TO A FULL STOP. YOU REALLY HAVE TO EXPERIENCE THIS ON YOUR OWN TO UNDERSTAND HOW SCARY AND NERVE WRECKING IT IS WHEN YOU HAVE VEHICLES ABOUT TO RAM YOU FROM BEHIND BECAUSE THE SUV SIMPLY WOULD NOT ACCELERATE. MANY TIMES, I HAD TO SWERVE BACK IN TO ORIGINAL LANE IN FEAR OF CAUSING A SERIOUS ACCIDENT. BECAUSE OF THIS, I DON'T EVEN LET MY WIFE DRIVE THE VEHICLE. SERVICE MANAGER WAS KIND ENOUGH TO RESEARCH ON THIS MATTER AND FOUND BULLETIN #PIP4112J AND HE CAN'T REALLY DO ANYTHING. I'VE BEEN EXPLAINED THAT DUE TO LARGE POWER FROM THE ENGINE, HE HAS SEEN THE REAR OF THE VEHICLES BREAK APART. I FULLY UNDERSTAND THE SERVICE MANGER'S POSITION ON THIS BUT I THINK THIS IS A MAJOR SAFETY CONCERN AND SOMEONE CAN SERIOUSLY GET HURT BY THIS. *KB