Ignition switch, key fob or immobilizer failure on the 2008 Mercury Mountaineer
When ignition switch, key fob or immobilizer failure gets reported
Owners of the 2008 Mercury Mountaineer report ignition switch, key fob or immobilizer failure at a median of 70,000 miles. A quarter of the reports come in before 35,000 miles and a quarter after 75,000 miles, from 14 reports that carried an odometer reading.
A part like this is normally expected to survive 85,000 miles. It is the 3rd most-reported problem on this model year.
The mileage distribution
The reported range runs from 20,000 miles at the tenth percentile to 90,000 miles at the ninetieth, a spread of 68,402 miles across the middle 80% of reports.
When the reports scatter this far, the mileage is telling you about how these cars were driven more than about the part itself.
36% of the dated reports were filed under 36,000 miles.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| 21,000 miles | 35,000 miles | 71,400 miles | 73,800 miles | 89,402 miles |
Read the 10th percentile as “one report in ten arrived this early”. Exact figures are shown in this table because it is the table of record; everywhere else on the site they are rounded to the precision the sample can carry.
What a percentile can and cannot tell you here
These five numbers describe the readings owners gave, in order. The median is the middle one: half the reports arrived below it. The 10th and 90th are the edges of the bulk of the distribution, and the distance between them is the part worth reading. A tight spread — say 70,000 to 95,000 miles — points at something that wears out on a schedule, and the schedule is knowable. A wide one, 20,000 to 190,000, points at a fault that hits some cars and never troubles others, which means the mileage on the listing in front of you tells you very little about your odds.
What these figures are not is a survival curve. Every reading here comes from a car whose owner filed a complaint, so the sample contains only failures: it cannot say what share of the fleet made it past 150,000 miles untouched, because those owners had nothing to report. Nor is the mileage the moment of failure — it is the odometer reading as recalled at the time of filing, which may be weeks later and is sometimes rounded to the nearest ten thousand by the person typing it.
Percentiles are shown at all only once 8 readings exist for the vehicle and mode. Below that the middle of a handful of numbers is noise wearing a decimal point, so the figures are withheld rather than dressed up.
What happens, and what it costs
Putting it right typically runs $250–$1,500 at an independent US shop. That range is an editorial estimate held in this site's failure-mode catalogue, not a figure from NHTSA, and it is a repair cost rather than a diagnosis cost.
The same failure on other years
The same failure is reported on 4 model years of this car. It shows up earliest on the 2002, at a median of 35,000 miles, and latest on the 2007 at 170,000 miles.
By volume the 2008 is the worst of them, which makes this a problem of this specific year rather than of the model as a whole.
If one year stands out to the left, that is the year to avoid; if the whole line sits at a similar mileage, this is wear rather than a defect in one production run.
Tick median reported mileage Solid middle half of reports Faint 10th to 90th percentile Colour how bad the failure is when it happens
What owners wrote
Verbatim from NHTSA complaint narratives, trimmed for length. The mileage is the one the owner gave.
Tl* the contact owns a 2008 mercury mountaineer. The contact stated that while driving 25 MPH, the driver's seat moved all the way to the rear seats. The vehicle was taken to the dealer. ....updated 08-24-12 *bf the consumer stated the selling dealer was unable to duplicate the failure. The local ford dealer, croft (williams) sayre, pa discovered a loose ignition switch which corrected the problem. Updated 08/30/2012 *js
The driver's seat moved back while braking for traffic same as if I had turned off the car and was removing the key. A few minutes later it happened again while braking. I realized it was happening while braking because when my leg moved towards the brake pedal, my knee touched the key chain, thus it appears to be a problem with the ignition switch, not the brakes, causing the problem. I contacted my local ford service shop and they advised they have never heard of this problem and do not know how to fix this as they have not received any bulletins from ford about the problem. I am taking it to their shop and hope that they can re-created the problem as they advised this is the only way they can try and find something to fix as they will not replace the ignition based on my information. *tr
Purchased a used 2008 mercury mountaineer almost a year ago, in approx oct 2012 the driver's seat started moving back and forth while driving. When the seat moved back it was almost so far back I couldn't hold onto steering wheel or keep foot on brake pedal. Took vehicle to mccoy mills ford and they could not duplicate occurrence. Since that date this has happened multiple times and I figured out it has something to do with the ignition switch. If the car gets any minor jolt as in riding on rough street or going over speed bump, ignition apparently shift which triggers something in the sensor and off you go. Most recent occurrence was on 12/11/2012 while driving through a local walmart parking lot; slowly went over speed bump and seat started moving on its own. Since the occurrences are becoming more frequent decided to take care back in now that I know it has something to do with ignition switch. Called ford customer care center and spoke to a rep who stated they didn't have any recalls for such a matter and my bumper-to-bumper had expired so I would have to incur cost to repair. Went back to mccoy mills ford was told that the…
Also reported on the 2008 Mercury Mountaineer
Other body or interior problem
Other electrical problem
Other lighting problem
Other powertrain problem
Other engine problem
Control module (ECM/PCM/BCM) failure
How far this goes
Complaints are voluntary, so 17 is a floor and not a count of affected cars. Mileages are typed in by owners and cluster on round numbers. And the mode itself is assigned by software reading the complaint text, which is reliable in bulk and fallible one report at a time.
Questions this page answers
At what mileage does ignition switch, key fob or immobilizer failure happen on the 2008 Mercury Mountaineer?
Across 14 owner reports that included an odometer reading, half were filed by 70,000 miles. A quarter were filed before 35,000 miles and a quarter after 75,000 miles. These are the mileages owners reported when they complained, not a prediction for any individual car.
How common is ignition switch, key fob or immobilizer failure on the 2008 Mercury Mountaineer?
17 reports have been filed with NHTSA, about 34 per 1,000 vehicles. Complaints are voluntary, so this is a floor rather than a count of affected cars.
What this is and is not. These are the mileages at which owners chose to complain to a federal agency, which is not the same as the mileage at which the part fails on every car. It skews toward failures that happened outside warranty, cost real money, or frightened someone. It is still the only public dataset that carries failure mileage at all, and the shape of a few hundred readings is informative even when a single one is not. Methodology · JSON · this failure on other cars
Source Owner complaints and recall records published by the US National Highway Traffic Safety Administration, model years 1996–2027 Figures rebuilt Published by AtWhatMileage How every figure is computed