Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2009 Mercury Mariner owners, lightly cleaned up (personal details are redacted by NHTSA).
While traveling approximately 35 MPH, driving in a straight line on a city street in traffic, the ABS abruptly applied the brakes - hard! The ABS light came on and a "check brake system" warning message was displayed. Also, the electrical system shut down and the engine lost power. After about 5 seconds, power was restored and vehicle was able to proceed. This occurred approximately 8 times over a two mile distance. During the last 4 times, the engine died, lost power completely, and needed to be turned off and restarted to continue. This failure was a dangerous safety hazard. Vehicle was towed to albuquerque Lincoln Volvo. The problem was diagnosed as a failed ABS module, 9l8z. The dealer replaced the ABS module with a faultly module. A second ABS module was installed and the vehicle was deemed repaired. The dealer did not return the defective part for analysis.
Power of vehicle drastically decreased while driving down secondary road. Had just enough power to pull over to side of the road. Pushed down accelerator in park and neutral but no power. Turned off. Restarted and resumed normal driving. Suspect electronic throttle body. The Ford dealership will not replace without a diagnostic fee because they state it is not a recall, although an internal vehicle health report states "there are recalls for your 2009 Mercury Mariner at this time" notice # 13n03 electronic throttle body extended coverage I believe using the word recall constitutes misrepresentation when in fact Ford motor company states it is just a customer satisfaction program to alleviate them from costs and any wrong doing. It is a very dangerous safety concern.
Tl* the contact owns a 2009 Mercury Mariner. The contact stated that while driving approximately 25 MPH, the vehicle hesitated and lunged forward as the engine warning indicator illuminated. The contact powered the vehicle off and back on and drove the vehicle without incident, however, the failure recurred approximately two weeks later. The contact powered the vehicle off and back on, however, the vehicle failed to accelerate. The vehicle was towed to an independent mechanic and was diagnosed that the throttle actuator needed to be replaced. The vehicle was repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 89,000.
On 1/1/2016 I was driving on 495 w in queens, ny heading back to manhattan where I live. Out of nowhere the car began jerking, a wrench light on the dash panel came on (which I never saw before) and I could tell the car was decelerating. I tried hitting the accelerator again, the car would jerk, the engine was revving but was barely moving. I knew I had to pull over and luckily I was able to navigate to the shoulder of the road. This was an extremely dangerous situation. I am a confident driver, however, a less confident or timid driver most likely would have panicked and gotten into a potentially serious collision.
Tl* the contact owns a 2009 Mercury Mariner. While driving on an incline at an unknown speed, the vehicle suddenly decelerated and would not accelerate when the accelerator pedal was pressed. The service engine light illuminated prior to the failure. The vehicle stalled and was able to be restarted. The vehicle was taken to an independent mechanic where it was diagnosed that the electronic throttle control failed. The vehicle was not repaired. The manufacturer was not notified. The VIN was unavailable. The failure mileage was 118,000.
Tl* the contact owns a 2009 Mercury Mariner. While driving approximately 55 MPH, the vehicle began to shutter, the engine stalled, and the service sensor light illuminated. Five minutes later, the engine was restarted and the failure recurred after approximately fifteen minutes. The failure occurred on multiple occasions. The cause of the failure was not diagnosed. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 79,000.
Tl* the contact owns a 2009 Mercury Mariner. The contact stated that while driving at 45 MPH, the throttle body failed and there was a sudden loss of acceleration. The contact applied force to the accelerator pedal and it did not respond. The contact was not included in NHTSA action number: pe13003 (engine). The vehicle was taken to the dealer but was not diagnosed or repaired. The manufacturer was notified of the failure. The approximate failure mileage was 61,000.
Mercury Mariner (2009) v6 4wd. Has stalled twice. 1. While driving at 35 MPH. It stalled and was able to restart once the vehicle stopped on the side of the road. We took it to a Ford dealer and the throttle body was replaced. 2. Stalled when slowing to a stop. This was after the throttle body was replaced on 10/13/2017. Only driven about 500 miles. Both times vehicle was going down a country road.
Tl* the contact owns a 2009 Mercury Mariner. The contact stated that while at an intersection making a left turn, the power steering failed. The check engine warning light illuminated. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 125,000. The VIN was not available.
My 2009 Mercury Mariner (has 56,000 miles), without any warning, it just shut off while I was driving it. Has happened twice. Was able to get the side of the road and was able to restart it. No warning lights came on at all. Car is at dealership now to have it checked out.
NHTSA investigations
Electronic Throttle Body Malfunction
On February 21, 2013, the Office of Defects Investigations (ODI) opened Preliminary Evaluation PE13-003 to investigate allegations of electronic throttle body (ETB) failures resulting in sudden reduction of engine power in model year (MY) 2009-2013 Ford Escape, Fusion, Mariner and Milan vehicles.
Engine complaints in other Mariner years
Frequently asked questions
How common are engine problems on the 2009 Mercury Mariner?
NHTSA has 60 complaints about the engine & cooling of the 2009 Mercury Mariner, 19% of the model year's 315 complaints.
Is there a recall for 2009 Mercury Mariner engine problems?
No. NHTSA lists no engine & cooling recall for the 2009 Mercury Mariner, though it has 1 recall for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2009 Mercury Mariner engine problems start?
Half of the complaints with a recorded mileage happened before about 69,000 miles, and 9% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.