I have an ammonia smell, worse than a rotten egg, under hard acceleration, that comes through the vehicle vents and into the cabin, even with all windows up and vents on recirculation or outside air. Many sequoia owners have reported this to Toyota, and they have no known fix. The odor that comes into the cabin burns your eyes for a few seconds, as well as makes my passengers and I nauseous, and…
2010 Toyota Sequoia engine problems
severe 12 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Failure mileage
Complaints
12
Recalls
0
Avg fix
$3,100
1fire
2injuries
When does it fail?
Of the 12 engine complaints filed for the 2010 Toyota Sequoia, here's the actual mileage breakdown — failures cluster heaviest at 0-25,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Engine accounts for 39% of every owner complaint on file for this vehicle — the dominant problem area across 3 categories tracked.
Among the 6 model years of Toyota Sequoia in our records for engine problems, this one ranks #3 by owner-complaint volume.
The failure pattern owners describe
Buyer takeaway: The 2010 Sequoia has serious thermal and combustion issues: bumper melting during normal towing is widespread and Toyota acknowledges the problem but offers no recall fix; one owner experienced a complete engine fire shortly after dealer service. Valve spring breakage around 117K miles and unintended acceleration are also reported.
The 2010 Sequoia has a systematic exhaust thermal problem when towing. Six separate owners report rear bumper melting, blackening, and smoking around the exhaust pipe while pulling trailers rated well within factory limits. Two note the exhaust doesn't clear the bumper like it does on competing tow vehicles; one owner bought an aftermarket tip to fix it. Toyota replaced one bumper but made no design changes. One dealership acknowledged multiple complaints and said they were "working on a solution"—but another refused coverage claiming warranty had expired. Owners consider this a fire hazard.
A separate engine fire occurred minutes after the owner pulled out of a parking lot following a 30K service; flames came from under the hood and consumed the vehicle.
At 117,000 miles, a valve spring broke on the highway, forcing speed reduction. The owner found the same failure pattern in other Sequoias at comparable mileage.
One owner reported a rotten-egg smell under acceleration that burns the eyes and causes nausea; Toyota has no known fix.
An air injection pump and switching valve replacement at 103K miles and an unintended acceleration incident (after prior pedal replacement by Toyota) round out the reports.
Same Toyota Sequoia engine reports on nearby years: 2007
Failure modes owners describe
Exhaust-induced bumper melting during towing
Rear bumper melts and burns around the exhaust pipe when towing trailers within factory weight limits. Multiple owners report blackening, melting plastic, smoking, and burning odor. Two owners note exhaust design does not adequately clear the bumper compared to other tow vehicles.
When: During or immediately after trailer towing; complaint #7 reports it on brand new vehicle
Symptoms owners cite: Rear bumper melted and discolored black around exhaust area; Burning plastic smell in cabin and exterior; Smoking from bumper area; Foul odor detected during fuel stop
Repairs/costs cited: Toyota provided replacement bumper in at least one case (#2). One owner purchased aftermarket exhaust tip that resolved issue. Dealership in complaint #3 stated nothing was wrong with tail pipe and refused to address beyond warranty.
Recalls/TSBs owners mention: Complaint #7 reports Toyota rep acknowledged receipt of multiple complaints and stated they were working on a solution. Complaint #3 dealership declined repair citing warranty expiration. Complaint #10 reports dealership notification on three separate occasions with no corrective action.
Ammonia/rotten egg smell under acceleration
Strong ammonia or rotten egg odor enters cabin under hard acceleration, burns eyes, causes nausea, and distracts driver. Owner reports many Sequoia owners have reported this to Toyota with no known fix.
When: Occurs under hard acceleration
Symptoms owners cite: Ammonia or rotten egg smell worse than typical sulfur; Odor enters cabin through vents even with windows up and recirculation on; Eye burning lasting a few seconds; Nausea in passengers; Driver distraction
Recalls/TSBs owners mention: Complaint #4 reports Toyota has no known fix
Valve spring breakage
Valve spring broke while driving on highway at approximately 117,000 miles. Owner reports finding multiple instances of the same failure in other Toyota owners with same engine at similar mileage.
When: 117,000 miles
Symptoms owners cite: Vehicle shudder while driving on highway; Requirement to reduce speed
Check engine light – air injection and switching valve
Check engine warning light illuminated. Dealer diagnosed moisture and condensation in air injection pump and air switching valve, though dealer acknowledged they could not verify specific issue but flagged parts as needing replacement as preventive measure.
When: 103,000 miles
Symptoms owners cite: Check engine warning light illuminated
Repairs/costs cited: Air injection pump and air switching valve replaced. Owner notes vehicle was out of warranty (warranty is 150,000 miles or 10 years, whichever comes first).
Recalls/TSBs owners mention: Manufacturer notified of failure. Warranty coverage ended.
Unintended engine acceleration
Engine revved up on its own without accelerator being depressed while driving. Accelerator pedal and carpet had previously been replaced by Toyota.
When: After accelerator pedal and carpet replacement by Toyota
Symptoms owners cite: Engine sudden rev without depressing accelerator
Recalls/TSBs owners mention: Owner contacted Toyota; Toyota did not respond.
Engine fire
Engine made noise on start; flames and smoke came from under hood while pulling out of parking lot. Vehicle burned within minutes. Vehicle had recently completed 30K service at Toyota dealer and was running in excellent condition prior to incident.
When: Shortly after 30K service
Symptoms owners cite: Noise on start; Flames and smoke from under hood; Entire vehicle burned
Synthesized from 12 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 8 most recent
In june 2010, took family vacation from virginia to disney world. Pulled travel trailer rated below tow rating (7,000 lbs). When arrived, noticed that the rear bumper melted all around the exhaust. Exhaust does not clear the bumper. If you look at other tow vehicles, the exhaust pipe clearly is away from the vehicle. The excess load from pulling the trailer creates excess heat. Reported the…
While towing 6000 lb travel trailer heat exiting the exhaust has melted rear bumper cover near exhaust tip. Everything on vehicle is factory original and should not be melting from excess heat generated by towing within factory specified weight limits. Poses a fire risk.
Discovered rear bumper was severely burned around tail pipe after pulling a trailer. I purchased the vehicle new from modesto Toyota. I brought the vehicle to modesto Toyota and reported the problem as a factory defect. They inspected the problem and reported back to me that there was nothing wrong with the tail pipe and because it was beyond the warranty period there was nothing they would. I…
2010 Toyota sequoia. Brand new. Bumper began to melt from extreme heat emitting from exhaust pipe. Strong smell of smoke in vehicle. Brought to Toyota. Had Toyota rep. Inspect. He stated that Toyota has rec.'d. Other complaints of same and that they are working on solution. I feel that this is a fire hazard. *tr
While pulling our travel trailer with our 2010 Toyota sequoia limited 5.7, upon stopping to fuel up the bumper around the exhaust pipe had melted and was smoking. We noticed in the interior a foul smell, like a plastic burning but couldn't figure it out. We stopped to fuel up and I checked under the hood and then discovered where the problem was. The tow vehicle was well within limits according…
I bought the vehicle under the assumption that it only had 138,000 miles on it. Upon trying to register it with Carfax I was informed that the odometer had been tampered with and the actual mileage is 345,000
The contact owns a 2010 Toyota Sequoia. The contact stated that the check engine warning light was illuminated. The vehicle was taken to an unknown dealer to be diagnosed. The contact was informed that there was moisture and condensation in the air injection pump and the air switching valve. The contact stated that there was a manufacturer’s warranty pertaining to the failure causing the check…
Had engine trouble with your 2010 Toyota Sequoia?
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 2010 Toyota Sequoia?
It's a meaningful issue. 12 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $3,100.
At what mileage does the engine typically fail?
Across the 8 complaints that reported odometer mileage, most engine failures cluster between 19,255 and 103,000 miles, with the median around 92,500. A quarter of owners report trouble before 19,255; a quarter make it past 103,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
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/2010/Toyota/Sequoia.
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.