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 2003 Mercury Mountaineer owners, lightly cleaned up (personal details are redacted by NHTSA).
On 9/2/06, I used my vehicle to go to store and while at the store, I had difficulty placing the vehicle into park and needed to shut vehicle off to finally lock it into park. I then returned home with the vehicle and parked it in my driveway. The vehicle then rolled down the driveway and crashed into my house and struck my 8 month old son 's stroller. It caused damage to my house and vehicle received damage to the windshield, front bumper, hood and grill. I immediately called the dealer and was given an appointment to bring it on 9/11/06. After examining the vehicle , the dealer stated that they recommended replacing the brake shift interlock switch since they have been found to stick and be faulty in other mountaineers. I was told that although this was a safety hazard, it was not a recall and not covered under my warranty. …
Big o techs conned wife into buying 2 tires and we own AWD SUV that requires 4 at the same intervals .I immediately notify them that this is not safe and will damage my car they continued for over 2 months to lie to me about having somemone comtact me . I have all the communications I've had with them through messages. A few weeks after they put the tires on and refused to take them off and put my old o es back on and issue a refund well my transmission and transfer case failed I contacted them again and again they lied to me about someone contacting me . I took my SUV to the transmission shop we measured over 2 inch circumference difference. I informed big o that I have a TSB issued by Ford my employer that dates back to 2011 on tire circumference procedures for tire dealers to follow . The response I got was that big o refuses to review or acknowledge tsbs . …
Tl contact owns a 2003 Mercury Mountaineer. While driving 65 MPH, the contact noticed smoke coming from the front and rear of the vehicle. She then heard a loud bang and the steering wheel began to shake. The vehicle lost power, but did not shut off. The vehicle was towed. The Ford dealer diagnosed the vehicle as needing the front end differential replaced. The vehicle was repaired, but the failure recurred when the contact picked up the vehicle. Since then, the front end differential has been replaced five times. The Ford dealer was unable to diagnose the cause of the continuous failures of the replacement part. The contact also stated that the rear liftgate is cracked. A valid VIN was unavailable. The current mileage is 64,000 and failure mileage was 60,000.
Tl* the contact owns a 2003 Mercury Mountaineer. While driving, the transmission failed to shift. While parked, the emergency brakes failed and caused the vehicle to roll away. The contact was able to gain control of the vehicle. In addition, the brake warning indicator illuminated. The vehicle was towed to the dealer where it was diagnosed that the brake lines and hoses needed to be replaced. The vehicle was repaired, but the issue recurred. The manufacturer was made aware of the failure. The failure mileage was 200,000.
Tl contact owns a 2003 Mercury Mountaineer. While the vehicle was on in the park position with the automatic start, the gear shifted into reverse and crash into a vehicle. The contact called to the police who confirmed that the vehicle was in the park position. The contact is concerned about the safety risk since the failure May have caused a serious injury or tragedy to occur. The vehicle was not destroyed. The failure mileage was 112,000.
Last December the engine revved and accelerated very high, around 6,000 rpms. Afterwards, the transmission engaged, acceleration lowered and the transmission changed gears while entering a street in oncoming traffic. When attempting to accelerate the engine revved but the vehicle did not move. Attempted this 3 times to no avail. On 4th attempt the transmission engaged and the vehicle moved. The vehicle was taken to the dealer. The dealer said it was the solenoid pack and an oil additive that they believed were causing the problem. They performed the repairs. The problem recurred in June. Took the vehicle back to the dealer. The dealer found nothing on the diagnostic machine and could not duplicate the problem. The problem recurred again in July. Took the vehicle to the dealer and again the dealer could not find anything wrong. …
We bought our Mountaineer new in 2003. We have had numerous problems, but the worst has been with the transmission. We have consistently taken our vehicle to dealerships for service, but are continually told that they cannot "replicate the problem at this time". The transmission has always shifted hard, but dealerships simply tell us it just shifts hard. In January of 2006 the overdrive light was flashing and the check transmission light went on. I took it into the dealer who told us we had to have the torque converter replaced as they found metal shavings in the pan. We paid over $1300 believing this would solve the shifting problem, it did not. At the end of June I took it into another dealership for an oil change and trip inspection. I mentioned again that it shifts hard. …
Upon leaving work in the am I started my vehicle and none of my dash gauges were working nor were any of the electric window or the radio. I then called my mechanic who adv me to bring it to him. While I was en route to take my vehicle to him it started making a weird noise like I was in a helicopter and I started smelling this weird smell like oil burning at first it thought they messed up my oil change and I was furious. Upon arriving at the shop he immediately smelled the odor put it up on the lift and found out that my front differential had gone bad. …
Purchased the 2003 Mercury, Mountaineer, AWD vehicle new on 6/17/03. On 05/10/06 at 50515, the left front hub bearing had to be replaced. A visual exam indicated water damage with bearing seizure. On 11/24/08 at 88826, the same problem as the earlier hub replacement was diagnosed. At this time both the left and right front bearing hubs had to be replaced. The right front hub was practically frozen and showed signs of heat fatigue to the outer casing. Both hubs showed rust and pitting. I maintained possession of both hubs for future reference. There is no doubt in my mind that had the hub locked up on the highway while traveling at highway speeds, (70mph) a potential for a rollover accident existed. On 11/21/06, a rear differential noise was diagnosed. The rear differential was rebuilt. On 11/24/08 the noise was again heard coming from the rear. …
I drive my husband's 2003 Mercury Mountaineer it has 69000 miles on it now and we bought it used dec 2004. When the SUV shifts into 3 or 4th gear it clunks or shutters. We have taken it in to the dealers several times having it returned and told there is nothing wrong. In December 2007 we took it in again with the same complaint and they did a transmission flush. Now when accelerating up to 35 the RPM would raise up to 4,000, like it was slipping.then it shift into wrong gear. The overdrive off light on the dash started flashing. Next day service engine soon light is on. We took it to dealership they claim they won't know what is wrong with it until they take it apart and it could cost any where from $3,000 to $4,000. …
NHTSA investigations
Vehicle Rollaway Allegations
This investigation is being closed based on several considerations.By the most inclusive counting of all alleged rollaway incidents (i.e., counting all alleged rollaway incidents and assuming a singular failure mechanism), the incident rate is low, however during EA09-013, ODI identified a number of different failure mechanisms in 180 incidents related to the alleged defect.The highest rate for any particular…
Transmission complaints in other Mountaineer years
Frequently asked questions
How common are transmission problems on the 2003 Mercury Mountaineer?
NHTSA has 42 complaints about the transmission & drivetrain of the 2003 Mercury Mountaineer, 28% of the model year's 152 complaints. The component named most often is automatic transmission (19 mentions).
Is there a recall for 2003 Mercury Mountaineer transmission problems?
No. NHTSA lists no transmission & drivetrain recall for the 2003 Mercury Mountaineer. 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 2003 Mercury Mountaineer transmission problems start?
Half of the complaints with a recorded mileage happened before about 78,000 miles, and 13% before 25,000 miles.
Is it dangerous?
Owners linked 5 crashes, 3 fires and 3 injuries to transmission & drivetrain problems on this model year. If you notice symptoms, have the car checked before driving further.
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.