The Powertrain Control/Emissions Diagnosis (PC/ED) manual has been revised for diagnosing electronic throttle bodies (ETBs). The ETC_ACT and ETC_DSD PIDs should not used to diagnose possible ETB concerns. The IDS has a limited refresh rate when reading these PIDs and cannot display quickly enough to validate a concern. The PCM automatically monitors these inputs more accurately and will set diagnostic trouble codes (DTCs) when appropriate. Using these PIDs for diagnostics will lead to inaccurate results and improper ETB replacements. If a concern is intermittent and no DTCs are present, refer to historical DTCs and the PC/ED, Section 3 No DTCs Present Index chart for further information.
full bulletin at NHTSA ↗2005 Mercury Mountaineer engine problems
moderate 8 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Failure mileage
Complaints
8
Recalls
0
Avg fix
$3,100
When does it fail?
Of the 8 engine complaints filed for the 2005 Mercury Mountaineer, here's the actual mileage breakdown — failures cluster heaviest at 0-25,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
No new NHTSA engine complaint has been filed on this vehicle in over 9 years — the issue may be aging out of the active population.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering engine on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
FORD/LINCOLN/MERCURY: IF BATTERY WAS DISCONNECTED OR DEAD, VEHICLES/TRUCKS MAY EXPERIENCE HARD STARTS AND ENGINE IDLE RPM FLUCTUATION AND EXHIBIT DIAGNOSTIC TROUBLE CODES (DTCS) P0505, P0506, P2111 AND P2112.
full bulletin at NHTSA ↗SOME 1997-2008 VEHICLES EQUIPPED WITH A 4.6L 2V, 5.4L 2V, OR 6.8L 2V ENGINE--SPARK PLUG THREAD REPAIR PROCEDURE--NOT COVERED UNDER NEW VEHICLE LIMITED WARRANTY. THIS INCLUDES F-53 MOTORHOME CHASSIS. UPDATED 2/23/10.
full bulletin at NHTSA ↗WDS COP KIT DIAGNOSTIC TIP - COIL ON PLUG (COP) IGNITION SYSTEMS - ENGINE MISFIRE OR ROUGH RUNNING.
full bulletin at NHTSA ↗NO START/HARD START ON COLD SOAK - 4.0L ENGINE.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
What owners are reporting 3 most recent
On two occasions the engine cut out while driving the car, all the engine warning lights came on. Once the car was safely off the road and placed in park it would start and continue to operate. The Ford dealer said that there was not fault code in the computer, they could not duplicate the failure and could not find any fault in the engine system. Ford service representatives said I should go a…
Tl*the contact owns a 2005 mercury mountaineer. While driving 35 MPH, the vehicle stalled and the engine shut off. This has occurred three times since 2006. The failure is most common while driving down an incline and when the cruise control was activated. The check engine light was illuminated and the power steering does not operate normally. The vehicle restarted after ten to fifteen…
As I was driving the vehicle just died; all the warning lights came on and as I was losing speed I pulled over to curb the best I could. Restarted car and it seemed to run fine but happened again 20 minutes later. This has also happened 2 other times within the last 10,000 miles of driving. *tr
Had engine trouble with your 2005 Mercury Mountaineer?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the engine problem on the 2005 Mercury Mountaineer?
It's a documented issue but not catastrophic. 8 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Across the 8 complaints that reported odometer mileage, most engine failures cluster between 35,000 and 126,000 miles, with the median around 73,000. A quarter of owners report trouble before 35,000; a quarter make it past 126,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $3,100 for engine repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to engine?
No active recalls currently cover engine issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2005/Mercury/Mountaineer.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.