SOME 2008-2017 FORD/MERCURY/LINCOLN VEHICLES EQUIPPED WITH SYNC MAY GENERATE A VHR THAT IDENTIFIES A CONCERN WITH THE BRAKES AND SUSPENSION CATEGORY INDICATING SERVICE IS REQUIRED DUE TO A BRAKE SYSTEM WARNING LAMP BEING ILLUMINATED. IF THE PARK BRAKE WAS APPLIED WHEN THE VHR WAS GATHERING DATA FROM THE MAJOR VEHICLE SYSTEMS, THE BRAKES AND SUSPENSION MESSAGE WILL BE REPORTED AS THE VHR LOOKS FOR ANY WARNING LAMPS ILLUMINATED IN THE INSTRUMENT CLUSTER. RERUN THE VHR WITH THE ENGINE ON AND VEHICLE IN PARK, AND ENSURE THE PARK BRAKE IS DISENGAGED. IF THE SYNC VHR IS STILL REPORTING A CONCERN TO THE CUSTOMERS SYNC OWNERS ACCOUNT, REFER TO THE APPROPRIATE WORKSHOP MANUAL SECTION FOR DIAGNOSIS BY
full bulletin at NHTSA ↗2009 Mercury Mariner brakes problems
severe 11 complaints filed with NHTSA · avg repair $450 · see brakes across all vehicles →
Failure mileage
Complaints
11
Recalls
0
Avg fix
$450
2crashes
1injury
What stands out
No new NHTSA brakes complaint has been filed on this vehicle in over 3 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 brakes 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.
SOME 2008-2017 FORD/MERCURY/LINCOLN VEHICLES EQUIPPED WITH SYNC MAY GENERATE A VHR THAT IDENTIFIES A CONCERN WITH THE BRAKES AND SUSPENSION CATEGORY INDICATING SERVICE IS REQUIRED DUE TO A BRAKE SYSTEM WARNING LAMP BEING ILLUMINATED. IF THE PARK BRAKE WAS APPLIED WHEN THE VHR WAS GATHERING DATA FROM THE MAJOR VEHICLE SYSTEMS, THE BRAKES AND SUSPENSION MESSAGE WILL BE REPORTED AS THE VHR LOOKS FOR ANY WARNING LAMPS ILLUMINATED IN THE INSTRUMENT CLUSTER. RERUN THE VHR WITH THE ENGINE ON AND VEHICLE IN PARK, AND ENSURE THE PARK BRAKE IS DISENGAGED. IF THE SYNC VHR IS STILL REPORTING A CONCERN TO THE CUSTOMERS SYNC OWNERS ACCOUNT, REFER TO THE APPROPRIATE WORKSHOP MANUAL SECTION FOR DIAGNOSIS BY
full bulletin at NHTSA ↗FORD/MERCURY: ABS MODULE SELF TEST CREATING A SLIGHT VIBRATION IN ACCELERATOR/BRAKE PEDAL AT 12MPH (20KM/H) AND/OR 42MPH (68KM/H). THE ABS MODULE WILL INITIATE A ONE TIME SELF TEST AT 12MPH AND AT APPROXIMATELY 42MPH FOR EVERY KEY ON CYCLE.
full bulletin at NHTSA ↗FORD/MERCURY: ABS MODULE SELF TEST CREATING A SLIGHT VIBRATION IN ACCEL/BRAKE PEDAL AT 12MPH (20KM/H) AND/OR 42MPH (68KM/H). THE ABS MODULE WILL INITIATE A ONE TIME SELF TEST AT 12MPH (20KM/H) AND AT APPROXIMATELY 42MPH (68KM/H) FOR EVERY KEY ON CYCLE.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners of 2009 Mercury Mariners describe sudden, intermittent brake failures where the pedal goes soft, travels excessively toward the floor, or becomes unresponsive despite extreme pressure. Failures happen without warning—at highway speeds, approaching intersections, or while driving 40 mph—and sometimes resolve temporarily after restart or brake bleeding, only to recur days or weeks later.
The most common culprit cited is a sticking valve in the ABS hydraulic control unit (modulator valve), which Ford acknowledged in Recall #19S54 for select 2006–2010 vehicles. That recall specifies a normally closed valve sticks open, reducing braking capacity. One owner notes Ford's recall fix involves switching from DOT 3 to DOT 4 brake fluid and a new cap, raising questions about fluid type being a root cause.
Power brake booster and power brake assembly electronics have also failed, with one owner needing replacement twice (2013 and 2014) at a dealership, only to learn the part is no longer manufactured. Owners report spending $1,200–$2,600 on repairs—new master cylinders, brake lines, ABS components, EHCU units—yet the problem persists. One family's daughter was involved in an accident due to brake failure; another owner states the vehicle was unsafe to drive. Ford has denied assistance in multiple cases, and many owner VINs fall outside the narrow recall scope despite having identical symptoms.
Same Mercury Mariner brakes reports on nearby years: 2008
Failure modes owners describe
ABS Hydraulic Control Unit / Modulator Valve Sticking
A normally closed valve inside the ABS hydraulic control unit (modulator valve) sticks open or becomes slow-responding, bypassing portion of the brake system and causing extended brake pedal travel or complete loss of braking.
When: 86,000–170,000 miles; failures occur intermittently without warning
Symptoms owners cite: Brake pedal goes to the floor or requires excessive pressure to depress; Loss of approximately half the brake system; Soft, unresponsive brake pedal; Brakes fail suddenly during driving (e.g., at highway speeds, approaching intersections); Pedal travel distance increases significantly; Issue disappears temporarily after restart or brake bleeding
Repairs/costs cited: Owners cite replacement of modulator valve (Ford part 9L8Z-2C346-C), hydraulic control unit (EHCU) ($2,100–$2,600 cost range cited), and power brake module components. One owner reported part BM6Z-2455-A (power brake assembly) no longer available from Ford as of 2013 failure.
Recalls/TSBs owners mention: Ford Recall #19S54 applies to select 2006–2010 Ford Fusion, Mercury Milan, and Lincoln MKZ vehicles with sticking valve in ABS hydraulic control unit; recall involves pressure-flushing system with DOT 4 brake fluid and replacing DOT 3 reservoir cap with DOT 4 cap. Multiple owners report their 2009 Mercury Mariner VINs were not included in recall despite identical symptoms. Campaign #19V904000 (Service Brakes, Hydraulic) cited by one owner; VIN not covered.
Power Brake Booster / Power Brake Assembly Failure
Power brake booster assembly or its electronics malfunction intermittently, causing loss of brake assist and hard or unresponsive pedal.
When: February 2013 (first failure); January 2014 (second failure, 2009 model year)
Symptoms owners cite: Brake warning signal illuminates on dashboard; Brake pedal requires hard pressure to floor; brakes do not respond normally; Loss of power brake assist; Issue disappears temporarily upon vehicle restart
Repairs/costs cited: Dealership replaced booster brake assembly, bush, and module. Later failure required replacement of power brake assembly electronics (part BM6Z-2455-A), which became unavailable from Ford; owner sourced part from scrapped vehicle.
Brake System Component Cascade Failures
Multiple brake components fail or require repeated replacement (master cylinder, brake lines, ABS power assistant), but underlying issue persists, suggesting a systemic or root-cause defect not addressed by individual part swaps.
When: Intermittent failures over months; no specific mileage noted
Symptoms owners cite: Brake pedal goes to the floor without warning; Brakes unresponsive or fail to stop vehicle; Failures occur on and off despite repeated repairs; Soft pedal
Repairs/costs cited: Owners report replacing master cylinder, brake lines, ABS power assistant, new brake pads, and brake bleeding; brakes continue to malfunction despite repairs. One repair shop charged for canister purge valve replacement (likely unrelated diagnostic error by dealer).
Recalls/TSBs owners mention: Ford customer service refused to provide documentation or assistance in one case (CAS-28178357 and CAS-27857368); dealership reported being unable to verify concern and unable to provide permanent fix.
Synthesized from 11 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 1 most recent
While driving vehicle brakes all of sudden go to the floor, no pedal response. This has happened a couple of times without warning. Once when I was approaching an intersection and light changed. My brakes all of the sudden went to the floor and I had to downshift and cut my wheels toward the curb to stop from crashing. Then a couple days later attempting to get it to mechanic it was fine and…
Had brakes 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 brakes problem on the 2009 Mercury Mariner?
It's a meaningful issue. 11 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $450.
At what mileage does the brakes typically fail?
Across the 8 complaints that reported odometer mileage, most brakes failures cluster between 90,000 and 150,000 miles, with the median around 116,175. A quarter of owners report trouble before 90,000; a quarter make it past 150,000. 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 $450 for brakes 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 brakes?
No active recalls currently cover brakes 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.