Ford Mustang sudden acceleration problems

Filed Aug 3, 2026 · Transmission · WA

The 10-speed automatic transmission on my 2020 Mustang failed internally at approximately 18,073 miles. The vehicle began shifting harshly at low speeds with an intermittent clunk. While driving, the transmission would slip slightly and then either surge forward or hesitate with a dull thud before engaging. The behavior was unpredictable and worsened over time. No warning lamp ever appeared and no diagnostic trouble codes were stored, so the driver gets no advance notice of this condition. This is a safety hazard when pulling into traffic, turning across an intersection, or merging. When power arrives late, abruptly, or not at all, the driver cannot judge a gap in traffic reliably. An authorized Ford dealer verified the concern on a test drive, confirmed the vehicle failed the CDF clutch cylinder leak test, and documented an internal tapping noise in Drive and Reverse. Fluid level was in spec. The dealer performed Ford TSB 25-2475, which addresses harsh and delayed shifting on this transmission: the unit was removed, torn down on the bench, the CDF cylinder replaced, and the unit reassembled and reinstalled. It did not correct the concern. The dealer's written notes state the concern was still present, the TSB did not cure it, and the transmission has an internal failure requiring replacement. Independent transmission specialists I consulted all recommended full replacement rather than rebuild, citing known problems with this transmission in this model year. Ford has revised multiple technical service bulletins on harsh and delayed shifting for this transmission over several years. My vehicle failed at roughly 18,000 miles, far under the 60,000-mile powertrain warranty limit, but Ford declined assistance because the five-year time limit had passed.

Filed Jan 8, 2024 · Acceleration, Airbags · 43,000 miles · NH · crash · 1 injury

The contact owns a 2016 Ford Mustang. The contact stated that with the transmission in the reverse position and while reversing from a parking space, the vehicle suddenly experienced unintended acceleration, reversed, and crashed into a second vehicle. After shifting to the drive position, the vehicle immediately accelerated forward causing the driver to lose control of the steering and crash into a tree. During the incident, while pressing the brake pedal the vehicle did not stop and after crashing head-on into a tree the airbags did not deploy. The driver sustained an injured ribs which did not require medical treatment. A police report was taken at the scene and the vehicle was towed away. The contact indicated that five other parked vehicles were damaged during the incident. The cause of the failures was not determined. The manufacturer and local dealer were not yet contacted. The failure mileage was 43,000.

Filed Dec 18, 2023 · Brakes, Engine · MO

I have a 2008 Ford Mustang with a V-6 engine. Recently I had to jump start it twice in a week's time to get it started and decided to take it to my dealer to have the battery checked. On the way there, I had to stop for a line of line of traffic at a red light. The instant I applied the brakes the engine started racing. I stood on the brakes as hard as I could, but could not bring the car to a complete stop. I got it slowed down to about three MPH, steered it into a parking lot that was next to me, and shoved it into park. I was afraid to drive it, so I called AAA and had it towed to my dealer. I told them how the engine started to race when I applied the brakes, and that I couldn't bring the car to a complete stop. They wrote it up that the engine started running rough when I applied the brakes. That is not what I told them. They made no written reference to the unintended acceleration. This struck me as odd. Their analysis of the vehicle showed that the master cylinder and brake power booster had failed. They told me that sometimes when these components fail they can cause the engine to rev. My engine more than revved, it sounded like it was racing at full throttle. The incident shook me up quite a bit. It also seemed odd to me that two major brake components would fail at the same time. I had gotten new front and read brake pads earlier in the years and no other brake issues were discovered. Though the car has been repaired and seems to be OK, I'm somewhat skittish about driving it. I'm aware that there was a class action law suit filed against Ford in 2013 for 2002-2010 Ford vehicles claiming unintended acceleration. Though the suit was dismissed, I'm worried that the problem still exists. I know for a fact that my foot was fully on the brake pedal, and that the floor mat played no role in this issue. I had no similar issues with the car in the fifteen years prior.

Filed Dec 30, 2022 · Transmission · IL

After slight acceleration and then light braking vehicle wants to lunge forward and is a outright safety hazard in 3 separate incidents it almost caused an accident and one was a pedestrian, fors is well aware of this vehicles incidents and well documented by text from dealer acknowledging such incidents

Filed Dec 16, 2022 · Brakes · 4,000 miles · CA · crash

The contact leased a 2021 Ford Mustang from an Enterprise rental company. The contact stated while driving approximately 3-5 MPH and coming to a complete stop, the brake pedal was depressed but the vehicle failed to respond, lunged forward, and hit the rear of the vehicle before him. The contact stated that it was a fender-bender; however, the front of the vehicle sustained damage. The air bags did not deploy. There was no warning light illuminated. The contact did not sustain injuries. The occupants of the other vehicle did not sustain injuries. There was no police report filed. The contact was able to continue driving. The dealer was notified of the failure and informed the contact that there was no recall associated with the failure. The vehicle was returned to Enterprise rental company. There was no further information provided. The manufacturer was not notified of the failure. The failure mileage was approximately 4,000. The VIN was unavailable. .

Filed Dec 7, 2022 · Engine · NC

I have taken my vehicle to Ford. Called Ford as well. And when at a stop, and while in drive, my car will lunge/ jerk and if my car was behind a vehicle too close could hit it. I also believe that If a person were in front of the vehicle it could lunge forward into them. I see in google that many 2019 mustang owners have reports this as well. This jerk/ lunge has happened a hand full of times. Two Ford dealerships and ford.com have advised they do not have reports from consumers on this.

Filed Nov 26, 2021 · WV

Purchased vehicle new It took me a long time to understand what the issue was. I complained to Ford and they gave me account rep that has never driven manual transmission. When I contacted Ford the end result was they have found nothing and car is operating normally. My issue : "driver assist" on clutch. It auto revs the throttle and is extremely inconsistent. I can forward to 20 second videos it needed. Problem is with the clutch and brake pedal. Releasing brake pedal causes engine to rev anywhere from 900-1500 rpm. Problem is driving in slow traffic scanario when you have have to two-foot clutch and brake. Engine will want to take off. I have had almost two near rear end collisions. The rev is uncontrollably inconsistent. One example: I was following a car running 2 miles per hour in an ally. Not following that close. At normal idle the mustang is about 5 miles per hour so I was catching them. I pushed clutch and brake to slow down. Then released the pedals the car unexpectedly surged forward. The problem wouldn't be so bad if it were consistent or would be disabled if the car is already moving.

Filed Oct 27, 2021 · Transmission · TX

10 speed Ecoboost transmission, doesn't stay in gear and delayed shifts causing acceleration problems. Hard shifts, jerking, and hard lunge forward when shifted into Drive. The forward lunge is unstoppable even with the brake fully engaged. Transmission slip when changing gears while driving. Yes, it's available for inspection. Yes, mine and others safety risk are at risk. Yes, the problem has been reproduced and confirmed by a dealer. Inspected by an authorized dealer/manufacturer. NO other warning lamps or messages.

Filed Apr 16, 2021 · Acceleration · FL

2020 ford mustang. Consumer writes regarding accelerator safety incident. *ld the consumer stated the vehicle experienced unintended acceleration while being driven. The dealer was notified and could not replicate the failure.

Filed Nov 10, 2020 · Lights · 35,000 miles · FL

Suddenly started experiencing a loss of power at highway speeds only remedied by slamming the accelerator to the floor which then caused the car to surge forward. After getting the car home also noticed the rear brake lights would remain on at all times. The twin problems ended up being connected. Turns out there is a small plastic/ceramic piece in the brake assembly that fails and breaks apart without warning - also no dashboard warnings after it fails. Causes the vehicle to think the brakes are being applied and cuts the power in response. This happened while traveling at interstate highway speed and was an immediate safety issue. Was told by the dealer this small part is very susceptible to florida heat - unfortunately the whole brake assembly has to be replaced.