2021 Ford Bronco Sport: start-stop system problems

Filed Apr 29, 2025 · Transmission · MS

This is a correction and expansion to complaint #11650564. My 2021 Ford Bronco Sport has now experienced complete transmission failure at approx. 86,000 miles, following earlier rear differential (RDU) failure at 60,600 miles. Both major drivetrain components failed well before expected lifespan under normal, mostly interstate driving. The vehicle has never been off-roaded. Transmission symptoms include shuddering, fluttering, failure to engage park, and severe gear engagement issues. Critically, the vehicle would power forward while placed in neutral — it was not rolling. The wheels received torque while in neutral, which should not happen. Reverse gear would also engage forward motion, and drive would fail to engage at all unless I toggled 4WD low. Park would not hold the vehicle, requiring the parking brake to prevent movement. One serious safety incident occurred when stop-start activated at a red light and the car failed to re-engage drive, leaving me stranded in live traffic. In another case, reverse engaged late and suddenly surged backward near a building. I scanned the vehicle using FORScan and found a code for stuck solenoid A (failure to engage park). I asked the dealer to check the valve body — they refused, claiming the transmission was “shot” without verifying the issue. Ford issued SSM 49930, internally on Aug 5 2022 acknowledging these behaviors in this transmission. These are not just mechanical issues — they are dangerous. I respectfully request the federal safety agency investigate the 8F35 transmission used in the 2021 Bronco Sport.

Filed Mar 31, 2025 · Electrical · VA

The car went completely dead when I was stopped at a red light. There was no power and I couldn’t put it into park. There was no indicator light nor warning that there was a problem with the battery. This put me into great risk of being hit by another car as traffic started to worsen and cars were trying to go around me. Police came and got me out of the car and because they could not get the car into gear they called and had it towed. I incurred the cost of the tow as well as the cost of the battery and the labor to install it. I tried to get reimbursed from the dealership but they said they couldn’t help me abc suggested instead that I don’t use the auto stop/start because it was draining the battery which caused it to not have enough power to restart at the red light. This was a very frightening experience as it was in another city other than my own and it was just on the other side of a bridge during traffic hour.

Filed Jan 24, 2025 · Electrical · 59,340 miles · AL

The contact owns a 2021 Ford Bronco Sport. The contact received notification of the federal safety agency Campaign Number: 25V019000 (Electrical System); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The contact stated that the Auto START/STOP technology failed to start the vehicle while depressing the accelerator. The contact had to connect a portable charger to be able to restart the vehicle and continue driving. The failure recurred and the engine failed to restart. The vehicle was towed to a certified mechanic who diagnosed and determined that the battery was drained and needed to be replaced. The vehicle was repaired. The dealer was not contacted. The manufacturer was made aware of the failure and informed the contact that the part for the recall repair would be available approximately in April 2025. The manufacturer referred the contact to the federal safety agency Hotline to report the failure. The failure mileage was 59,340. VIN tool confirms parts not available.

Filed Dec 11, 2024 · Transmission · AR

Bought 12-1-23 got recall 24V‑267 fix and then the vehicle started to die at red lights if the autostart/stop wasn't turned off. On 12/9/24 apparently the turbo went out. Unsure how only 95,345 miles. The driver window get stuck down anytime at a drive thru. Will have to turn off vehicle completely and restart for it to roll back up.

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.

Filed Sep 19, 2024 · Brakes, Electrical · OH

The vehicle was traveling on a major highway when at a red light the car stopped and the auto start/stop engaged and the car turned off. After the car turned off I could not restart it. All power to the car was lost. No lights, radio, nothing. I attempted to put the car in neutral to move it off the highway, however the car is designed in a way it can not simply just be shifted into neutral. I grabbed the owners manual and read I needed to pull the manual park release cable located under the steering wheel. I pull the cable nothing. At this point I’ve called the local police department and they send out 2 officers. They attempt to shift the car into neutral as well, to no luck. I read the electronic parking break needs to be turned off but the car needs power to do this. My car has no power. A man comes with a jumper box and attempts to jump the car when it starts smoking. The battery has full voltage however it’s not transferring power to the car. I have to sit in the middle of a highway for 2 hours until a tow truck can tow my car. In those 2 hours I was at a significant risk of bodily and property damage and also risking harm to the other drivers on the road. Ford has no suggestion how to fix my specific problem. They’ve not taken into account a situation where there is no power to turn off the electronic parking break, to pull the cable and shift the car into neutral. The Ford service department had no idea how to replicate the situation to try and fix it. All I asked Ford for was a way to safely be able to remove my car from the middle of traffic the next time it happens. They have told me they can not help me. The Delaware city police department sent two officers who witnessed the event. Prior to the loss of power there was no warning. $1000 later I had a new starter put in and Ford did some recall work on it. However in my opinion the car is unsafe in the event power is lost again on the road.

Filed Sep 16, 2024 · Electrical · 40,000 miles · TX

The contact owns a 2021 Ford Bronco Sport. The contact stated that while the vehicle was idling at a stop light with the automatic Start/Stop feature activated, the driver depressed the accelerator pedal and the vehicle instantly shut off. The vehicle was not able to be restarted and a tow truck was called to the scene. While examining the vehicle, the tow truck driver discovered that the battery in the engine compartment had exploded. The battery was replaced, and the vehicle was restarted and operated normally. The cause of the failure was not yet determined. The local dealer was contacted, and an appointment was scheduled. The manufacturer was not yet contacted. The failure mileage was approximately 40,000.

Filed Sep 10, 2024 · Electrical · NY

I was in the turning lane at a light and the Bronco died completely. No power at all. The brakes were locked and I could not get in neutral. Police came to push the vehicle out of traffic but we didn’t know how to get into neutral. After googling that part we were able to push into a parking lot. I had to pay for a tow truck ($125) and towed to the dealer. When they called they said the Bronco went into safety mode because the battery was low. I said why didn’t the battery light go on. There was no warning just a dead vehicle at a busy intersection. We are lucky no one rear ended us because we had no access to the hazard lights. Dealer thinks that the auto start stop kicked in while waiting for the light and the battery didn’t have enough volts to start the vehicle again causing the whole car to shut down. Really that is a horrible feature because again it was dangerous to have cars angrily pull around you because you are sitting there. I couldn’t imagine with the car being black what would of happened at night! The dealer changed the battery and claimed there is no other issue even though the car gives no notice of anything wrong.

Filed Aug 28, 2024 · Electrical · PA

Over the past the month the vehicle has expereinced a sudden loss of power/ complete electrical failure twice. The first was in a parking space in a parking lot, the second was in the middle of busy intersection. Both times were promted by the vehicle's automatic start/stop function.

Filed Feb 7, 2024 · Electrical · AZ

While at stop light, engine shut off (auto start-stop). Wouldn't restart, car would not move, automatically went into park, wouldn't go into neutral to be moved, and was stuck. Had to manually release the vehicle into neutral to be moved. Battery was completely dead, replacement solved the issue. Battery was less than 2 years old. Approx. 50k miles.