Huge win for car owners! All TSBs to be made public. The Center for Auto Safety just made the NHTSA (US Government) make public the full text of all TSBs from now on. They are the same organization that has petitioned the NHTSA & filed lawsuits to protect car owners over exploding gas tanks & other major safety issues. Whenever you drive in your car, you are safer thanks in part to a lot of work over the years by this small but very effective consumer advocacy group.

Please take a moment & say thank you by donating $5 or whatever you can to the Center for Auto Safety.

NHTSA — Vehicle Speed Control Problems


really awful
Crashes / Fires:
12 / 1
Injuries / Deaths:
8 / 0
Average Mileage:
20,237 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2005 Mercury Grand Marquis engine problems

engine problem

Find something helpful? Spread the word.
Get notified about new defects, investigations, recalls & lawsuits for the 2005 Mercury Grand Marquis:

Unsubscribe any time. We don't sell/share your email.

2005 Mercury Grand Marquis Owner Comments (Page 1 of 2)

problem #25

May 132015

Grand Marquis

  • 87,000 miles


Unintended accel. Sometimes when I step on the brake the car accelerates instead. At first I thought it was me and my big feet. After some internet research I find it may be common as the 2005 gets older. I asked if brke pedal could be adjusted so that there was no interference with the gas pedal, I was told no. I had the master cylinder replaced, minimum improvement. One day I "shot" across US19 in ross township when I braked. Instead of stopping at a red light, I kept going until I cleared traffic in both directions ruining 2 wheels & tires - subsequently repaired. The car now sits in our driveway, after some other occurrences without incident. I'm leary of driving it & don't want to sell it & get someone injured or killed. Fortunately I have a 2004 Sable which I drive daily with no such problems! ideas?

- Pittsburgh, PA, USA

problem #24

Nov 092015

Grand Marquis

  • 144,000 miles
The contact owns a 2005 Mercury Grand Marquis. The contact stated that the vehicle failed to accelerate over 60 mph. When the vehicle was able to reach speeds more than 60 mph, the traction control warning light illuminated intermittently. The vehicle was taken to an independent mechanic where the failure was undetermined. The vehicle was not repaired. The VIN was not provided. The manufacturer was not notified of the failure. The approximate failure mileage was 144,000.

- Philadelphia, PA, USA

problem #23

Dec 292014

Grand Marquis

  • 40,000 miles
Started vehicle to move it in my driveway. Put it in drive and throttle stuck open and vehicle slammed my garage corner. Tried putting it in park and it went into reverse (brake override did not work) instead and crossed street, went across neighbors landscaping stones and slammed into the house next door's front porch at which time the ignition shut down and the car came to a stop. Many thousands of dollars in damages to all three homes.

- Mckinney, TX, USA

problem #22

May 072007

Grand Marquis 8-cyl

  • 12,000 miles


Sudden acceleration. The car did this after starting it in the driveway. Upon placing the car in drive the car accelerated burning rubber in the driveway. Had to stand on brakes and turn ignition off to stop car. The second incidence happened while braking for a red light, I had to shift car into neutral to stop car. Unsure of mileage in this instance. Most recently while in South Carolina I was sitting at a red light with my foot on the brake the car suddenly accelerated and I had to shift to neutral to avoid rear ending car in front of me. (mileage 60,000).

- Essex, MD, USA

problem #21

Apr 152013

Grand Marquis

  • 15,000 miles
The contact owns a 2005 Mercury Grand Marquis. The contact stated that the lights intermittently turned on and off. The contact took his vehicle to an independent mechanic where they replaced the lcm light control module. The manufacture was notified and stated that there was no recall for the make and model. The contact also stated while driving the cruise control suddenly malfunctioned spontaneously. The contact again took to vehicle to a Ford dealer were they stated there was nothing wrong with the vehicle. The vehicle was not repaired. The manufacture again stated no there were no related recalls for his year, make and model vehicle. The approximate failure mileage was 15,000 miles.

- Elgin, IL, USA

problem #20

Feb 102013

Grand Marquis

  • 25,000 miles
The contact owns a 2005 Mercury Grand Marquis. The contact stated that the vehicle exhibited sudden acceleration and the engine rpms would idle abnormally very high seconds prior to the failure occurring. The contact was able to stop the vehicle by shifting into neutral. The contact took the vehicle to the dealer however, the dealer was unable to diagnose the failure. The dealer then recommended having the throttle body replaced but could not guarantee that the repair would remedy the failure. The failure mileage was 25,000.

- Pompano Beach, FL, USA

problem #19

Oct 072010

Grand Marquis

  • miles


The contact owns a 2005 Mercury Grand Marquis. The contact stated that the vehicle suddenly accelerated whenever the contact was braking to a stop. The failure recurred several times. The vehicle was not taken to the dealer. The failure mileage was unknown and the current mileage was 46,000.

- Leesburg, FL, USA

problem #18

Jul 052012

Grand Marquis

  • miles
The contact owns a 2005 Mercury Grand Marquis. The contact stated that the driver of the vehicle was traveling 10 mph when the vehicle accelerated up to 50 mph and the driver crashed into several trees. The vehicle was not destroyed and there were no injuries. The vehicle was towed to a repair shop but the cause of the failure was unknown. The manufacturer was not notified of the incident. The failure mileage was unknown. The VIN was unavailable.

- Hot Springs, AR, USA

problem #17

Jun 162012

Grand Marquis

  • 18,000 miles
The contact owns a 2005 Mercury Grand Marquis. The contact stated that while parking, he attempted to apply the brakes but depressed the accelerator pedal instead. The contact crashed against another vehicle as a result. There was no damage. The contact stated that the failure was due to how close the pedals were positioned to one another. The vehicle was taken to dealer, who offered no assistance. The manufacturer was not notified. The VIN was not available. The failure and current mileages were 18,000.

- Vermilion , OH, USA

problem #16

Jan 092012

Grand Marquis 8-cyl

  • miles
Upon starting up 2005 Mercury marquis (~24000 miles) and placing car into drive, car accelerated at a high rate of speed and crashed into a gas station pump. The car accelerator malfunctioned and was in a "jammed state". the driver immediately put right foot then both feet on brake trying to get the vehicle to stop. The car would not slow much less stop. Driver suffered very serious eye injury and currently has no sight in injured left eye. There is the risk of losing left eye. Passenger suffered fractured sternum and other bruising. Both driver and passenger are traumatized from this car accelerator malfunction.

- Spring Lake, NJ, USA

problem #15

Oct 012005

Grand Marquis

  • 150 miles


The contact owns a 2005 Mercury Grand Marquis. The contact stated that while driving at any speed and attempting to brake, the vehicle suddenly accelerated. The failure was experienced numerous times. The vehicle was taken to the dealer several times for the failure where the dealer test drove the vehicle, but was unable to duplicate the failure. The vehicle was then taken to a local mechanic for further inspection. The contact also experienced failures with the headlights. The headlights were replaced but the abnormal acceleration failure was not repaired. The VIN was not available. The failure mileage was 150 and the current mileage was 15,600.

- Longwood, FL, USA

problem #14

Sep 152005

Grand Marquis

  • 5,000 miles
The contact owns a 2005 Mercury Grand Marquis. While driving at approximately 10 mph and depressing the brakes, the vehicle suddenly accelerated until the brake pedal was released. Also, while parked, the contact depressed the brakes and the vehicle lunged forward. The failure recurred intermittently. The vehicle was not taken to the dealer for diagnostics or repairs. The VIN was not available. The approximate failure mileage was 5,000.

- Bel Air, MD, USA

problem #13

Feb 242011

Grand Marquis

  • 8,770 miles
The contact owns a 2005 Mercury Grand Marquis. While driving approximately 44 mph, the contact applied the brakes and there was an abnormal increase in engine rpms and the engine roared loudly. The vehicle attempted to accelerate but the contact applied the brakes abruptly. The vehicle then gradually began to decelerate to approximately 30 mph. He then disengaged the overdrive feature and once the vehicle reached a speed of 30 mph, the vehicle operated as normal. The vehicle was not taken to have the failure diagnosed or repaired. The failure and current mileage was 8,770.

- Elgin, IL, USA

problem #12

Nov 232009

Grand Marquis

  • 41,000 miles
Over the past several months, my 2005 Mercury Grand Marquis has suddenly stalled when I begin to accelerate after the car is stopped. It happened 3 times in forward mode and once in reverse. On two occasions, I had gotten several feet into the busy intersection and in one incident, an accident nearly occurred.

- Huntington Beach, CA, USA

problem #11

May 232009

Grand Marquis

  • 17,816 miles
Arrived at son's home and stopped in driveway with foot on brake when vehicle suddenly accelerated uncontrollably, spinning wheels in gravel driveway. Driver swerved to avoid hitting garage and ran head on into a pine tree resulting in severe damage to entire front end of vehicle (expect vehicle to be considered a total loss) and injuries to the driver and two passengers. Both driver and passenger airbags deployed. Prior to arriving at destination, driver had used the cruise control on the vehicle. Vehicle has not yet been moved and am currently waiting for insurance adjuster to inspect vehicle. Both driver and front seat passenger suffered severe bruising on face, arms, chest and abdomen, presumably from deployment of the air bags as well as from the seat belts. Rear seat passenger suffered a contusion on the forehead and a sprained hand. All vehicle occupants were transported to hospital for evaluation and released.

- Durham, NC, USA

problem #10

Feb 242009

Grand Marquis

  • 29,000 miles
The contact owns a 2005 Mercury Grand Marquis. In February of 2009, while pulling into a parking space at an unknown speed, the vehicle jumped the curb, raced over the median, and crashed into a tree. There were no injuries. A police report was filed. The vehicle was towed to the dealer. The technician test drove the vehicle and found no failures. The failure previously occurred on approximately three or four occasions. The failure mileage was 29,000.

- Merritt Island, FL, USA

problem #9

May 012008

Grand Marquis

  • 30,200 miles
Car was slowing for red light, stepped on brake, engine oversped, vehicle was uncontrollable, collided with pick up truck ahead, pick up was pushed into a compact car ahead. Air bags did not deploy. Clouds of smoke behind my car and tire marks on roadway confirmed brake pedal, not accelerator, was depressed. Car experienced a slight overspeed on a previous occasion.

- Old Orchard Beach, ME, USA

problem #8

Dec 032007

Grand Marquis 8-cyl

  • Automatic transmission
  • 13,000 miles
While parked at the end of her driveway, waiting for oncoming vehicles to bypass, the vehicle automatically accelerated, and made a half turn at 40 miles per hour. The vehicle, as a result, hit a tree. As a result, the windows were damaged, the front seats, where the occupants were seated, while wearing the seat belts, were thrown to the rear portion of the vehicle. She has had the vehicle inspected by her insurance Agency ( safeco) [engineer] ) who stated that this is definitely a result in an ECM manufacturers' defect. As a result, the vehicle is completely damaged. The occupants sustained severe whiplash, and pinched nerves. She can no longer place weight on her feet, which could result in severe back pain. She has had both knees replaced. She and her husband, have not been able to contact the manufacturer as of yet. The failure and current mileage 13,000. The police and ems did come to the scene of the accident were a police report was filed. --ds updated 02-19-08 updated 02/14/08

- Toledo, OH, USA

problem #7

Apr 152005

Grand Marquis 8-cyl

  • Automatic transmission
  • 500 miles
When vehicle brakes are applied, vehicle begins to accelerate. The vehicle requires extreme pressure in order to have it stop. On one occasion I was forced to pass a stop light. The vehicle has been taken to the dealership on these occasions however dealership is unable to replicate the problem. They have not replaced any parts and are now considering installing a "black box" to record the incident if it occurs in the future and figure out what is causing the problem.

- San Antonio, TX, USA

problem #6

Aug 262006

Grand Marquis 8-cyl

  • Automatic transmission
  • 5,500 miles
: the contact stated while backing out of a parking space at 5 mph, the brake pedal was depressed and the vehicle surged in reverse. The contact shifted into neutral, the engine revved, and the tachometer rose quickly. The vehicle was taken to a service dealer, where the dealer was unable to duplicate or determine the problem. The dealer told the consumer, the incident was due to driver error and when she applied the brake she inadvertently pressed the accelerator as well. Updated 09/11/06.

- Revere, MA, USA

Read the next 5 complaints »

Not what you are looking for?