2021 Ford Bronco Sport: hesitation when accelerating

Filed Oct 26, 2026 · Fuel system, Transmission · OH

The contact owns a 2021 Ford Bronco Sport equipped with an 8F35 automatic transmission. While driving between 25 and 45 MPH under normal acceleration, the vehicle experienced repeated violent hesitation, jerking, and lunging 4 to 5 times in rapid succession, accompanied by rapid RPM fluctuations between 2,000 and 3,000 RPM. The condition mimics an engine misfire or momentary stall and loss of motive power during acceleration, creating an immediate safety hazard and risk of rear-end collision in active traffic. The vehicle was taken to an authorized Ford dealership (Cronin Ford North) on September 30, 2026. The dealership verified and duplicated the complaint on a road test, monitored PIDs, and officially confirmed that the torque converter clutch (TCC) was slipping. Despite confirming mechanical slip, the dealership stated in writing that there were "no relevant articles," overlooking the published Ford Special Service Message SSM 54797 for 8F35 torque converter shudder below 60 MPH. The dealership recommended replacing the torque converter and main control valve body for over $5,200. When the owner declined due to cost, the vehicle was released back into service without answering the owner's written safety inquiry regarding whether the vehicle was safe to operate with verified drivetrain slippage. Additionally, the vehicle has an open safety recall (25S76) for which Ford corporate confirmed no remedy or parts are currently available. The vehicle has not stalled completely, but the severe hesitation and surging persist under normal acceleration. The manufacturer has not provided a resolution.

Filed Sep 15, 2026 · Engine, Fuel system · 124,000 miles · OH

The contact owns a 2021 Ford Bronco Sport. The contact stated that while operating the vehicle, exhaust fumes and a fuel odor entered the cabin, and the check engine warning light illuminated. The engine misfired, and the vehicle hesitated while driving. Upon inspecting under the hood, the contact discovered black soot in the engine compartment. The vehicle was taken to a local dealer for diagnosis, where the dealer determined that the piston solenoid, catalytic converter, and driver’s side lower control arm and bushing needed replacement. The contact stated that the PCM was previously replaced. The contact associated the failure with the federal safety agency Campaign Number: 26V340000 (Suspension); however, the VIN was not included in the recall. The manufacturer was notified of the failure. The failure mileage was 124,000.

Filed Apr 8, 2026 · Electrical, Engine · 52,000 miles · LA

The contact owns a 2021 Ford Bronco Sport. The contact stated that while driving on several occasions at various speeds, the infotainment screen went black or displayed a half-operating screen. An unknown warning light was illuminated with the message "Attention Needed - Service Engine Soon" displayed. The vehicle was taken to a dealer, and it was determined that Part Number: BE52 needed to be replaced. The vehicle was not repaired. The contact stated that while driving on several occasions at various speeds, the check engine warning light illuminated. The vehicle was taken to the same dealer where it was diagnosed, and determined that an unknown part needed to be replaced after retrieving DTC: P0496. The vehicle was not repaired. While the vehicle was parked, the vehicle hesitated while starting. The vehicle was taken to another dealer to be diagnosed, and it was determined that the battery charge was lower than 40 percent but did not need to be replaced. The vehicle was taken to another dealer where it was determined that the battery needed to be replaced. The vehicle was repaired, but within 24 hours there was an unknown warning light illuminated with an audible chime. The contact believed that the failure was associated with the body control module (BCM). The manufacturer was notified of the failure and a complaint was filed. The failure mileage was approximately 52,000.

Filed Mar 25, 2026 · Engine, Fuel system · KY

While driving, the vehicle stutters during acceleration, creating hesitation and inconsistent power delivery. This occurs during normal driving conditions and has not improved after being inspected by a dealership. The issue has been reproduced multiple times and remains unresolved. The vehicle was taken in for service, but no effective repair was provided, and the condition persists. There is an active recall related to a potential fuel injector defect, which may cause fuel to accumulate on top of the engine. The recall remedy is currently unavailable. Given the ongoing stuttering and known fuel system issue, there is concern this condition is related. This creates a safety risk, particularly when merging into traffic or accelerating from a stop, as the vehicle does not respond consistently. No warning lights have consistently appeared. The issue continues despite dealership involvement and lack of available recall repair.

Filed Feb 27, 2026 · Fuel system · 83,191 miles · NC

The contact owns a 2021 Ford Bronco Sport. The contact received notification of the federal safety agency Campaign Number: 25V467000 (Fuel System, Gasoline). While driving at an undisclosed speed, the check engine warning light was illuminated, and the vehicle began shaking and hesitated while accelerating. The vehicle was taken to a dealer, where it was diagnosed, and the failure was associated with DTC: P0456 EVAP (Very Small Leak in EVAP Emission Control System). The vehicle was not repaired. The manufacturer was notified of the failure. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The failure mileage was approximately 83,191.

Filed Dec 2, 2025 · Fuel system · 69,398 miles · GA

The contact owns a 2021 Ford Bronco Sport. The contact stated that while driving at an undisclosed speed, the vehicle hesitated after fueling. There was no warning light illuminated. The contact became aware of a gasoline-like odor while entering and exiting the vehicle. The contact received notification of the federal safety agency Campaign Number: 25V467000 (Fuel System, Gasoline); however, the part to do the recall repair was not yet available. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the failure and confirmed that the part was not yet available and that a notification letter would be sent when the part was available. The approximate failure mileage was 69,398.

Filed Sep 9, 2025 · Transmission · 75,000 miles · MI

The contact owns a 2021 Ford Bronco Sport. The contact stated that while driving at slow speeds and turning in either direction, there was an abnormal grinding sound coming from the rear of the vehicle. Additionally, while driving at various speeds, the vehicle shuddered and hesitated while accelerating. The vehicle was taken to the local dealer, who diagnosed the vehicle and determined that the rear differential and transmission were faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was not yet contacted. The failure mileage was 75,000.

Filed Sep 2, 2025 · MI

I am reporting a serious and recurring issue with the catalytic converter on my 2021 Ford Bronco Sport (1.5L EcoBoost), which has resulted in reduced efficiency and partial blockage, causing exhaust gases to enter the cabin and triggering engine code P0171. My safety and the safety of others have been compromised because exhaust fumes, including carbon monoxide, have entered the cabin, which is particularly dangerous as I am currently pregnant. In addition, the engine experiences RPM fluctuations and revs up on its own, sometimes hesitating during acceleration, creating a risk of loss of control or accidents, and reduced engine efficiency contributes to unpredictable vehicle behavior. The problem has been confirmed by a dealership, which diagnosed the catalytic converter inefficiency and provided a $2,000 replacement quote. This issue has been widely reported among other 2021 Bronco Sport owners, indicating a recurring problem. The vehicle has been inspected by the dealership, which ran diagnostics and verified the codes. Prior to the failure, the Check Engine Light illuminated, and I experienced exhaust fumes in the cabin, unusual odors, reduced engine performance, and RPM surges with hesitation during acceleration, first appearing around 80,000. This defect poses not only a serious safety hazard, but also environmental concerns, as the failing catalytic converter increases emissions of harmful gases, including carbon monoxide, hydrocarbons, and nitrogen oxides, contributing to air pollution and greenhouse gas emissions. I respectfully request that this issue be formally investigated by Ford and the federal safety agency for a possible recall, that consideration be given to goodwill or warranty coverage for affected vehicles, that guidance be provided for the safe operation of vehicles exhibiting this defect, particularly for pregnant passengers or others at risk, and that the environmental impact of this defect be considered during the investigation.

Filed May 30, 2025 · Transmission · VA

My vehicle has been jerking/hesitating upon acceleration and at times can barely move going up an incline at low speeds. This has been going on for over a year. Last year I was told by the Ford dealership that it was the RDU recall which did not make a difference, and they replaced the PTO which also did not resolve the issue. I took it back in for more diagnostics this week to the same Ford dealership and was told that the transmission was bad and required replacement - that the fluid was black with metal particles and the level was low although their regular oil changes reflect as recently as two weeks ago that the level and color of the transmission fluid was normal. No warning lamps or messages. I declined the replacement at this time as I feel that it is a manufacturer's defect. It is available for inspection.

Filed Apr 6, 2025 · Fuel system · SC

Purge valve went bad, it was causing the vehicle to try to stall and dropping down to very low rim, always happened after fueling and would sometimes hesitate to go when accelerator was pushed. I had it stall on my trying to pull on to [XXX] in Florida from an exit. That could have been very bad. And I've noticed way too many other people online and in forums having the same concern. Do to safety concerns i paid to have mine replaced but do not feel like it should have already went out this soon. The date i included below is for the last incident, this issues started over a year ago and has slowly gotten worse. I did mention this back then to my service dept but was told it just probably hadn't built up enough pressure in the tank yet after fueling. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Dec 16, 2024 · Engine · MI

Torque converter failure at 100,000 miles. Car hesitates when it accelerates creating delay when going from stop to start.

Filed Nov 14, 2024 · Electrical · 49,000 miles · WV

The contact owns a 2021 Ford Bronco Sport. The contact stated that upon attempting to start the vehicle, the vehicle failed to start and was jumpstarted. The message "Battery Saver Mode" was displayed on the infotainment system screen. Additionally, the contact stated that failure had caused the engine auto Start-Stop system to become inoperable, causing the engine to not restart automatically while attempting to resume driving from a complete stop. The contact stated that she had deactivated the engine auto Start-Stop system. The contact stated that upon accelerating from a complete stop, the vehicle hesitated to respond. The vehicle was taken to Advance Auto, where the battery was tested, and the contact was informed that the battery was in good condition and did not need to be replaced. The vehicle was taken to the dealer, where the battery replacement was recommended; however, the dealer informed the contact that there was no guarantee that the battery replacement would correct the failure. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and a case was opened. The failure mileage was approximately 49,000.