While driving the mariner at 45 MPH on a busy street, the engine went into limp mode, lost all acceleration and slowed to 5 MPH. I was nearly rear-ended by the truck behind me and was forced to pull up onto a sidewalk, damaging my tire. Pulled the codes on the car and got a p111 code. Did some searching on the internet and found that this is a common issue and an extreme safety hazard. I was…
2009 Mercury Mariner fuel system problems
moderate 15 complaints filed with NHTSA · avg repair $1,200 · see fuel system across all vehicles →
Failure mileage
Complaints
15
Recalls
0
Avg fix
$1,200
When does it fail?
Of the 15 fuel system complaints filed for the 2009 Mercury Mariner, here's the actual mileage breakdown — failures cluster heaviest at 75,000-100,000 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
Of the 4 model years of Mercury Mariner we track for fuel system problems, this one carries the most owner complaints on file — 15.
No new NHTSA fuel system complaint has been filed on this vehicle in over 12 years — the issue may be aging out of the active population.
The failure pattern owners describe
Owners consistently report sudden loss of acceleration and power while driving, with the vehicle entering limp mode and restricting speed to around 5 mph. The wrench light illuminates, and in many cases the check engine light follows. The problem typically resolves after the driver turns off the engine, waits a few minutes, and restarts—but it recurs unpredictably, sometimes multiple times in a single trip or spread across months. One owner had the throttle body replaced under warranty around 85,000 miles, only to experience the same failure again at higher mileage and be told a second replacement was not covered.
Dealers and independent shops have identified a faulty electronic throttle body as the culprit, with replacement costs ranging from $300 to $720 depending on whether labor and towing are included. Ford issued a recall on the part after some owners had already paid for repairs privately; one owner received a $167.85 reimbursement that did not cover the full cost of the work.
Separately, owners report fuel tank leaks and fuel spillage when topping off the tank. Ford allegedly directs owners not to top off the tank but provides no service bulletin or acknowledgment of the defect. One owner at 154,000 miles was told the fuel tank needed replacement and that the VIN was not covered under recall.
Failure modes owners describe
Electronic throttle body failure with limp mode
Loss of engine power and acceleration while driving, often triggered by aggressive throttling or normal driving conditions. Vehicle enters limp mode, reducing speed to 5 mph or stalling entirely. Wrench light illuminates. Power is temporarily restored by turning the engine off, waiting, and restarting.
When: Various mileages reported: 42,000 miles, 90,000 miles, multiple recurrences over months or years for some owners. One owner reported throttle body replacement at ~85,000 miles, then failure again at higher mileage.
Symptoms owners cite: Loss of all acceleration/power while driving; Engine enters limp mode, limiting speed to ~5 mph; Rough idle or stalling; Wrench light illuminates; Engine light may come on (P2112, P111 codes noted); Acceleration unresponsive to throttle pedal input; Problem resolves temporarily after restart
Codes mentioned: P2112, P111
Repairs/costs cited: Throttle body replacement cited in multiple narratives: $430 quoted by dealer (#1); $300-ish quoted (#2); $720.60 total with parts, labor, towing, taxes (#4); dealer reimbursed $167.85 under recall after owner paid privately (#4). One owner replaced throttle body under warranty 1.5 years prior, then required to pay for replacement again (#5). Another owner replaced throttle body in 2011, then failure recurred and replacement needed again in 2013 (#14).
Recalls/TSBs owners mention: Recall issued (mentioned in #4 after fact); Ford customer care offered payment plan (#1); Dealer diagnostics fee $106 (#1); one owner received $167.85 reimbursement from Ford dealer after paying $720.60 for private repair (#4). Some owners reported Ford dealership initially said 'no code, nothing we can do' (#1). Throttle position sensor noted as on backorder at dealership (#3).
Fuel tank leak at filler neck
Strong abnormal gasoline odor detected around vehicle, particularly when fuel tank is full. Independent mechanic identified leak at top of fuel tank.
When: Approximately 154,000 miles
Symptoms owners cite: Strong abnormal gasoline odor upon exiting vehicle; Odor strongest when fuel tank is full; Visible leak at top of fuel tank
Repairs/costs cited: Fuel tank replacement required. Owner did not pursue repair; vehicle was not repaired per narrative.
Recalls/TSBs owners mention: Manufacturer informed owner VIN was not under recall. Manufacturer referred owner to NHTSA for assistance. No recall or TSB mentioned.
Fuel spillage when topping off gas tank
Fuel leaks from fuel system when attempting to fill tank completely. Multiple owners report the issue; Ford allegedly instructing customers not to top off tank but offering no official service bulletin or notice.
When: Not specified; reported to affect 2009 and 2010 model years
Symptoms owners cite: Fuel spillage when attempting to top off gas tank at pump; Fuel leaks during refueling
Repairs/costs cited: No repair documented. Owner reports Ford offers no solution and instructs not to top off tank.
Recalls/TSBs owners mention: Ford will not fix; tells customers not to top off gas tank. No service bulletins sent to dealerships per owner report. Dealerships deny knowledge of problem.
Intermittent surge and power loss while driving
Engine surges and loses power at low speeds, then resumes normal operation after a restart. Fuel gauge may show empty despite full tank.
When: March 2013 first occurrence, recurred later same year
Symptoms owners cite: Engine surges and slows down at ~30 mph; Temporary loss of power; Fuel gauge reads empty when tank is full; Power resumes after engine restart
Repairs/costs cited: No repair note; owner restarted engine and issue resolved.
Synthesized from 15 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 1 most recent
Had fuel system trouble with your 2009 Mercury Mariner?
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 fuel system problem on the 2009 Mercury Mariner?
It's a documented issue but not catastrophic. 15 complaints have been filed. Repairs average $1,200 and most owners catch it before it causes a breakdown.
At what mileage does the fuel system typically fail?
Across the 15 complaints that reported odometer mileage, most fuel system failures cluster between 46,000 and 94,000 miles, with the median around 70,000. A quarter of owners report trouble before 46,000; a quarter make it past 94,000. 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 $1,200 for fuel system 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 fuel system?
No active recalls currently cover fuel system 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/2009/Mercury/Mariner.
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.