Engine exhaust makes vibrating noise similar to a leaf blower under acceleration. TSB issued due to common issue and GM refuses to recall or fix. Broken baffle/weld inside of front muffler/resonator on exhaust system under front passenger compartment. Issue getting worse. $2500 at local dealership to fix, with GM offering “assistance” to fix issue in the amount of $742 leaving the consumer…
2021 GMC Acadia engine problems
moderate 17 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
17
Recalls
0
Avg fix
$3,100
The failure pattern owners describe
Buyer takeaway: A 2021 Acadia owner should expect recurring catalytic converter and exhaust failures, thermostat problems, and fuel pump module issues that may strand you on the highway with minimal manufacturer support. Some failures occur below 40K miles, and TSBs exist for known problems that GM has not recalled.
Owners of 2021 Acadia report engine and drivetrain failures starting as early as 5,000 miles—one catastrophic piston failure caused complete engine shutdown on a mountain pass at highway speed. Catalytic converters fail repeatedly between 61K and 86K miles despite warranty repairs, with one owner experiencing engine seizure and total power loss after oil contamination from a converter repair went wrong.
Thermostats and coolant control valves fail at 32K–76K miles, triggering check engine lights and cooling fans that run after shutdown. One dealer reported performing seven thermostat repairs in a single week on Acadia models. Fuel pump power control modules fail without warning at stoplight speeds, stalling the vehicle; owners note identical failures have been recalled on other GM models but not the Acadia.
The exhaust system is persistently problematic: internal muffler/resonator baffles break or weld fails, producing loud rattling at 2,000–2,500 RPM. A TSB (PIT5863) was published in November 2021 for this issue, yet no recall followed. GM offers only partial repair assistance. Radiators develop corrosion and leak coolant as early as 32K miles. Throughout, owners report dealer acknowledgment of systemic problems, partial warranty coverage, and manufacturer refusal of extended assistance despite multiple failures on the same vehicles.
Same GMC Acadia engine reports on nearby years: 2019
Failure modes owners describe
Catalytic converter failure and mounting bracket issues
Catalytic converters fail prematurely with broken or loose mounting brackets, cracks, and leaks. Multiple owners report replacement under warranty, yet failures recur shortly after. One owner reports oil leaking into the engine from a botched catalytic converter repair, causing complete engine seizure and stalling at highway speed.
When: 61K–86K miles; some within 2 years of initial replacement
Symptoms owners cite: Rattling noise from exhaust; Loud revving noise; Sulfur smell; Engine seizure and loss of all power while driving
Repairs/costs cited: Catalytic converter replacement, mounting bracket repair, front pipe repair, oil change. Owners report repairs performed at GM dealership but failures persist.
Recalls/TSBs owners mention: Warranty coverage for initial and some follow-up repairs; no recall or extended support offered despite repeated failures.
Engine catastrophic failure (piston failure)
At 5,000 miles, engine experienced complete failure with blown pistons. Vehicle lost all power and stopped suddenly on I-70 at highway speed. Dealership confirmed defective pistons as a production defect. GM declined repurchase and offered only rebuilt engine; dealership eventually bought back the vehicle.
When: 5,000 miles (first drive into mountains)
Symptoms owners cite: Sudden complete engine shutdown; Engine explosion-like failure; All vehicle systems shut down without warning
Repairs/costs cited: Blown pistons confirmed by Auto Nation. Dealership offered rebuilt engine; owner refused due to safety concerns. Dealership later repurchased vehicle.
Recalls/TSBs owners mention: GM national refused to buy back vehicle or provide trip interruption compensation. Case reference SR9-8150020854.
Thermostat/coolant control valve failure
Thermostat or coolant control valve fails, causing check engine light and cooling fan to run continuously after engine shutdown. Owner #13 reports dealer has performed seven repairs in one week on Acadia models. Multiple owners charged high repair costs with minimal manufacturer assistance.
When: 32K–76K miles
Symptoms owners cite: Check engine light illumination; Coolant fan runs after engine off; Steering assist reduced warning; Coolant temperature issues
Codes mentioned: P1098 (coolant control valve fault)
Repairs/costs cited: Thermostat replacement; radiator and oil cooler replacement also required in some cases. Repair costs in the hundreds. Some repairs covered under warranty; others denied.
Recalls/TSBs owners mention: Recall N252508341 and N252508350 exist for 3.6L V6 but do not cover all affected VINs. GM declined monetary assistance in multiple cases.
Fuel pump power control module failure
Fuel pump power control module fails without warning, causing engine to stall at traffic lights and inability to restart or drive more than a mile. Multiple owners report similar failures on other GM models have been recalled, but not the Acadia.
When: Mileage not specified; incident occurred at stoplight during normal driving
Symptoms owners cite: Engine stalls at low speed (stoplight); Difficulty restarting; Loss of fuel pressure signal despite adequate fuel
Repairs/costs cited: Fuel pump power control module replacement. Owner reports dealers acknowledge seeing large numbers of these failures and note some owners have had accidents.
Recalls/TSBs owners mention: No recall issued for Acadia despite recalls on similar GMC/Chevy models from same year. Owner advocates for recall.
Muffler/resonator baffle and weld failure
Internal muffler or resonator baffle breaks or welds fail, producing loud rattling and vibrating noise that resembles a leaf blower. Issue worsens over time. TSB PIT5863 (Correction Review 21-NA-118) published 11/2/2021 addresses identical issue but no recall issued. GM offers only partial financial assistance.
When: 28K–39K miles; some complaints ongoing for 1.5 years
Symptoms owners cite: Loud buzz and rattle at 2,000–2,500 RPM; Vibration felt in passenger floorboard; Rattling from exhaust under acceleration; Noise worsens over time
Repairs/costs cited: Exhaust resonator or whole exhaust assembly replacement. Repair cost cited as $2,500; GM offered $742 assistance, leaving $1,758 customer cost. Some repairs not performed due to cost.
Recalls/TSBs owners mention: TSB PIT5863 issued but no recall. GM offering partial financial assistance ($742) for some owners; others denied assistance despite TSB existence.
Radiator premature corrosion and leakage
Radiator develops corrosion and leaks coolant at low mileage. One owner reports driver's-side radiator corroded; another reports radiator failure at 62K miles requiring replacement along with thermostat and oil cooler.
When: 32K–62K miles
Symptoms owners cite: Coolant leak; Visible corrosion on radiator; Engine overheating risk
Repairs/costs cited: Radiator replacement. Some repairs not completed due to cost. Oil cooler replacement also required in one case.
Recalls/TSBs owners mention: Manufacturer made aware but provided no assistance or recall.
Crankcase moisture and check engine light
Moisture appears in crankcase, triggering check engine light and diagnostic code P04FB. Owner reports failure occurred multiple times and was repeatedly covered under warranty but informed no permanent fix exists.
When: 37,000 miles
Symptoms owners cite: Check engine light illumination; DTC P04FB displayed
Codes mentioned: P04FB
Repairs/costs cited: Quick repair covered under warranty multiple times; owner informed no permanent fix available.
Recalls/TSBs owners mention: Warranty coverage provided; manufacturer not formally notified.
Synthesized from 17 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 3 most recent
Vehicle's engine incurred coolant temperature issues, set DTC code, and cooling fan ran after engine was turned off. Dealer diagnosed as thermostat failure and completed repairs. Dealer checked and found no service assistance for repair even though there was a back order for replacement parts and was secured through dealer in detroit current NHTSA id number 110243390 / mfg communication #…
GM need to be looked at for faulty Thermostats being put into vehicles. While driving the message "steering assist is reduced " You get to a safe place and shut you car off and the fan still runs. After speaking with my dealer today, he said he has done 7 in last week. And if you look online, everyone especially Acadia models is having this problem. Customers are getting charged…
Had engine trouble with your 2021 GMC Acadia?
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 2021 GMC Acadia?
It's a documented issue but not catastrophic. 17 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 17 complaints filed, engine issues most often appear around 41,544 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/2021/GMC/Acadia.
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.