Vehicle purchased 8/31/2025 October 20, 2025 "reduced acceleration" alert while driving on why up a significant grade with no way to pull off to the side of the road. Speed limitied to 35mph. Stopped by dealership pulled PO6DD code. Appointment made for November 12th. November 12, 2025 routine oil change and service noted "unable to duplicate concern on vehicly, currently no P06DD is…
2025 GMC Sierra engine problems
moderate 27 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
27
Recalls
0
Avg fix
$3,100
What stands out
Engine accounts for 31% of every owner complaint on file for this vehicle — the dominant problem area across 5 categories tracked.
Owners have filed 27 engine complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
The failure pattern owners describe
Multiple owners of 2025 GMC Sierra trucks (both 6.2L V8 gasoline and 3.0L diesel variants) report engine seizure and failure within the first few thousand miles. The 6.2L V8 shows a pattern: owners hear knocking or grinding, the truck enters reduced-acceleration mode (limp mode), then loses power completely. Dealers confirm excessive crankshaft end play and worn thrust bearings, with GM issuing Technical Service Bulletin 25-NA-307 requiring full engine replacement. Engine replacement has 2–3 month lead times due to volume of affected units.
The 3.0L diesel presents a separate failure mode: the DEF (diesel exhaust fluid) range calculation is exponentially flawed. When towing, the computer triggers a 1000-mile warning despite the tank being 60% full, then progressively restricts speed from 65 MPH down to 5 MPH, eventually locking the instrument cluster to show only DEF level while hiding critical gauges like engine temperature. GM Service Bulletin 24-NA-196 acknowledges the issue but provides no permanent solution.
Additional failures noted: air compressor failure with engine compartment knocking, excessive oil consumption (800–1000 mile intervals), low oil pressure with metal debris in oil, valve cover cracks from manufacturing, and unexplained transmission control module communication loss. One owner's truck shut down at highway speed in busy traffic and could not be restarted. Dealers consistently report no warning lights preceded these failures.
Same GMC Sierra engine reports on nearby years: 2022 · 2023 · 2024
Failure modes owners describe
Crankshaft Thrust Bearing Wear / Excessive End Play
Crankshaft develops excessive end play in the thrust bearing, leading to catastrophic engine failure. Owners report the issue is detected by dealer diagnostics and confirmed via TSB 25-NA-307. Engine seizure or grinding/knocking sounds precede total failure.
When: 3,181 to 26,634 miles; as early as 5,200 miles on some units
Symptoms owners cite: Abnormal knocking or grinding sounds from engine; Metal shavings in engine oil; Reduced acceleration warning followed by loss of power; Engine seizes or locks up without restart; Vehicle enters limp mode at low speed
Codes mentioned: P06DD, U1643, B1A76, P05D, U0075, U0101, U0146, U020C, U0265, U1614, U1616
Repairs/costs cited: Full engine replacement required; owners report 2–3 month lead time for replacement motors at dealership
Recalls/TSBs owners mention: GM TSB 25-NA-307 confirms crankshaft end play inspection and mandates engine replacement; non-mandatory technical service bulletin issued
DEF System Range Calculation Error (3.0L Diesel)
Diesel variant exhibits faulty DEF (diesel exhaust fluid) consumption estimation. Computer displays exponential countdown in remaining range despite DEF tank being 60% full or more. Triggers escalating speed restriction warnings and eventual 5 MPH limp mode, locking out instrument cluster from showing engine/transmission temperature during towing.
When: During towing of travel trailers; occurs early in ownership when trailer is connected
Symptoms owners cite: Exponential DEF range countdown (not linear mile-for-mile); 1000-mile DEF warning followed by 300-mile warning; Red DEF Low warning with speed restriction countdown; Progressive speed restrictions: 65 MPH, then lower limits, eventually 5 MPH; Instrument cluster locks to show only DEF level; safety gauges (engine/transmission temp) hidden; DEF tank never actually empty (still 60% full) when range reads zero
Repairs/costs cited: No permanent repair or solution prescribed by GM; issue noted on unresolved TSB 24-NA-196
Recalls/TSBs owners mention: GM Service Bulletin 24-NA-196 acknowledged but no permanent solution provided; issued September 23, 2024
Air Compressor Failure (A/C System)
A/C air compressor fails, producing abnormal knocking/chirping sounds in engine compartment when compressor engages. Rough idle diagnostic codes issued; compressor failure confirmed at independent diagnostics.
When: Approximately 18,000 miles
Symptoms owners cite: Abnormal knocking sound from engine compartment at idle; Sound ceases when A/C is turned off; Sound returns when A/C is activated; Rough idle condition
Codes mentioned: B1A76, P05D, U0075, U0101, U0146, U020C, U0265, U1614, U1616
Repairs/costs cited: Air compressor replacement; vehicle remained at dealer pending repair
DFM System Chirping/Squealing Noise (6.2L V8)
Cold-start and downshift conditions trigger intermittent chirping, squeaking, or squealing sounds from engine or transmission area on vehicles with dynamic fuel management (DFM) system. GM field engineer claims it is 'normal characteristic of DFM system' related to ignition timing; owner suspects early warning of lifter/pushrod or transmission failure.
When: Cold start at auto stop restart; downshift under 20 MPH to 12 MPH; 7,800 miles at complaint filing
Symptoms owners cite: Chirping, squeaking, or squealing sound at cold start following auto stop restart; Sound occurs during downshift under 20 MPH; Sound not present on comparable trucks with same engine/transmission; Noise present since brand new purchase
Repairs/costs cited: Multiple repair attempts and parts replaced; no resolution documented
Recalls/TSBs owners mention: GM technical service bulletin 22-NA-218 referenced; GM field engineer reviewed truck but no diagnostic documentation provided to owner
Low Oil Pressure and Metal Debris in Oil
Engine exhibits abnormally low oil pressure and metal shavings found in engine oil, indicating internal bearing or component wear. Vehicle enters limp mode and loses power. At 1,185 miles, issue detected at dealership.
When: 1,185 miles
Symptoms owners cite: Loss of power / limp mode activation; Low oil pressure condition; Metal debris visible in engine oil
Engine Valve Cover Crack
Valve cover develops crack causing major oil leak shortly after delivery. Dealership initially misdiagnosed as faulty valve cover gasket; actual issue was crack in valve cover casting itself. Owner suspects crack occurred on production line.
When: Discovered within days of vehicle pickup (purchased 300 miles away)
Symptoms owners cite: Major oil leak from engine; Visible crack in valve cover casting
Repairs/costs cited: Valve cover replaced; repair took 18 days (3/3/2025 to 3/21/2025)
Excessive Engine Oil Consumption
Engine consumes abnormal quantities of oil. Owner must add oil every 800–1,000 miles despite no visible oil stains on ground, indicating internal oil burning rather than external leak.
When: Approximately 18,000 miles; noted during routine oil changes
Symptoms owners cite: Oil level drops to require top-up every 800–1,000 miles; No external oil leaks or stains on ground; Internal oil burning suspected
Repairs/costs cited: Issue identified but repair not completed
Loss of Transmission Control Module Communication
Vehicle loses communication with transmission control module on CAN Bus 2, resulting in loss of power or inability to shift. One instance cleared after first dealership visit; later recurred.
When: October 20, 2025; recurred December 4, 2025; 6,800 miles at time of permanent diagnosis
Symptoms owners cite: Reduced acceleration alert and 35 MPH speed limitation; Loss of communication with transmission control module
Codes mentioned: P06DD, U1643
Repairs/costs cited: Diagnostics led to discovery of worn thrust bearing requiring engine replacement
Recalls/TSBs owners mention: TSB 25-NA-307 referenced for crankshaft end play inspection
Unexpected Engine Shutdown Without Restart
Engine shuts down completely while driving with no warning lights, leaving vehicle immobilized. Some instances include automatic shift to Park and engagement of parking brake. Vehicle must be towed; dealer diagnoses seized engine or loss of gear selection communication.
When: As early as 3,181 miles; noted at 21,100 miles in another case; one incident on I-70 at high speed
Symptoms owners cite: Complete loss of engine power while driving; No warning lights or messages prior to shutdown; Vehicle unable to restart after shutdown; Automatic shift to Park and parking brake engagement in some cases; Loud engine noises or grinding immediately before shutdown
Repairs/costs cited: Engine replacement required in all documented cases
Synthesized from 27 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 6 most recent
Truck started with a knocking noise in the engine that developed into a grinding noise. Dealer Service Department inspected and did a transmission tear down only to discover the issue is with the excessive play in the crankshaft. At 13K miles, the service department has stated the entire engine needs to be replaced.
We were traveling when it went into limp mode slowing our speed way down. We got it to a dealership and they determined low oil pressure and metal in the oil. My vehicle only has 1185 miles on it.
I got 3200 miles on my 2025 gmc 1500 6.2 engine. The engine crash. Knocking. Skund like its going to jump out. Been at dealer in columbus. Since Thursday. No one touch it
The engine seized and locked up leading to a catastrophic failure of my three month old 2025 GMC Sierra Denali at approximately 3,181 miles. The engine, the 6.2L V8, was listed as a recall engine by GM for model years 2021-2024. My 2025 allegedly "passed inspection" yet had the same catastrophic failure. The vehicle engine made loud noises and it sounded like parts were breaking. The vehicle no…
- On 9/23/2025 while driving down the main street, the vehicle unexpectedly shut down (engine stopped running) and would not restart. The vehicle is currently at Elevation GMC (Boone ,NC) waiting to be diagnosed. - Safety was put at risk by the vehicle unexpectedly shutting down in the middle the of rush hour traffic and not being able to be moved. - When it is was towed into the dealership and…
Had engine trouble with your 2025 GMC Sierra?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the engine problem on the 2025 GMC Sierra?
It's a documented issue but not catastrophic. 27 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Based on the 27 complaints filed, engine issues most often appear around 35,184 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $3,100 for engine repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to engine?
No active recalls currently cover engine issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2025/GMC/Sierra.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.