Which parts fail
Components named in complaints (automatic and manual transmissions, CVT, axles, driveshaft, 4WD/AWD).
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).
I have been intermittently losing power steering. The code is B1342. After researching, it looks like Ford is aware of this problem but is unwilling to fix the issue. This fix must be done at a dealership since it is a software issue and going to cost $2,000. Obviously losing power steering when going at fast speeds is incredibly dangerous for myself and others. There is no check engine light that comes on when the issue arises.
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.
Normal driving when suddenly there was no acceleration & the wrench light came on in the dashboard. Car was running but there was no acceleration & idled roughly. Mechanic put a diagnostic on it which read p2112 throttle control actuator system stuck closed. Binding throttle body stuck closed. There was no warning and the incident was very scary since I could not get out of the way of traffic. The car would go about 1mph until I was able to pull off the road. When the car was later shut off and restarted, acceleration returned. This is frightening as you do not know when it could happen and could cause a serious accident.
Transmission fluid leaking from left hand halfshaft seal on my automatic transmission. Took into shop to have it diagnosed, found out something is wrong with the bearings do to low fluid. Then I find out there is a service kit available for this seal issue, however we have not received any notice of such service kit being available. I'd like to know who is going to cover the $2500 its going to cost to have my transmission fixed as opposed to a few hundred dollars it should have cost me had I been aware of this service kit.
Driving my 2009 Mariner premier about 35/45 MPH when wrench symbol comes on indicating throttle control powertrain / transmission problem car is not accelerating properly and transmission is jerking when I step on the gas pedal and the car shakes vibrates and feels under powered. Got home and parked it. Started it up and now check engine light is also on. Is this covered by the recall for extended warranty from Ford ?
I was driving around 40 MPH and a light in my dash the symbol of a wrench appeared ,then my SUV I lost power going forward , it seemed the engine shut down , I was able to get off the road in very bad traffic with out getting into an accident . The traffic was very heavy and the SUV was very hard to control with out power.
While driving down the road anywhere from 20-55 MPH, the car seems to stall out and the accelerator no longer works. You have to pull over and shut the vehicle off and it will start again. Sometimes the same problem will occur again within seconds, minutes, or days later.
I am getting continual throttle body errors on my 2009 Mariner. It goes into low power mode so I can "limp home". It happens mostly on highways when I need to "punch it" and get alot of acceleration.
My vehicle started leaking fluorescent oil from behind the radiator. Apparently, it's the condenser. I have been told that the radiator lines run through the same system, and that if it is not repaired my transmission will eventually fail. This failure was explained to be the transmission locking up, and they said if I'm going over about 30 MPH it will be very dangerous. I am about 2,000 miles out of warranty, and the emails I have sent to Ford only get a response that they will be happy to take my money and fix it. Within a few months of buying it, the intake manifold had to be removed to repair something. Then, a transmission solenoid. Then, it was shifting funny -because it had very little fluid-noone could explain why. The vibration in the gas pedal at 42 MPH "could not be verified. …
Update to 01/30/13 complaint. I purchased car on 10/22/12 with 58,398 miles from a dealer. I started having issues late December 2012. I was having problem with car jerking into gear or being sluggish when accelerating. I took car to dealer on 01/29/13. Researched carfax information and found out that on 01/05/10 - transmission flushed and stated as replaced. 18,588 miles. 08/09/10 - transmission was removed to replace cooler. 28,372 miles. On 01/29/13 mechanic advised that transmission was leaking badly and that "press regulator valve sticking". 01/30/13 - transmission valve body replaced. 63,356 miles. 6 weeks after valve body replaced car started jerking again. Took car to dealer on 03/18/13...dealer suggested replacement of transmission, but extended warranty company said no...would only pay for transmission rebuild. 65,951 miles. …
Transmission complaints in other Mariner years
Frequently asked questions
How common are transmission problems on the 2009 Mercury Mariner?
NHTSA has 44 complaints about the transmission & drivetrain of the 2009 Mercury Mariner, 14% of the model year's 315 complaints. The component named most often is automatic transmission (3 mentions).
Is there a recall for 2009 Mercury Mariner transmission problems?
No. NHTSA lists no transmission & drivetrain 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 transmission problems start?
Half of the complaints with a recorded mileage happened before about 69,000 miles, and 12% 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.