Some 2009-2020 Ford and Lincoln vehicles equipped with turbochargers may exhibit an oil leak from the turbocharger oil supply or return tubes, O-rings or 6.7L pedestal gasket. Although oil may collect on the turbocharger, it is very rare for a turbocharger to leak oil. To isolate the source of the leak, refer to Workshop Manual (WSM), Section 303-00 General Information > Diagnosis and Testing > Engine > Engine Oil Leaks - Fluorescent Oil Additive Method procedure. When an oil leak is present at a turbocharger oil supply or drain tube, remove the affected oil tube and inspect for damage, and replace the O-ring seals, pedestal gasket or oil tube as required. Refer to WSM, Section 303-04. For c
full bulletin at NHTSA ↗2010 Ford Flex engine problems
moderate 29 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Failure mileage
Complaints
29
Recalls
0
Avg fix
$3,100
1fire
When does it fail?
Of the 29 engine complaints filed for the 2010 Ford Flex, here's the actual mileage breakdown — failures cluster heaviest at 25,000-50,000 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
Owners have filed 29 engine complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Among the 9 model years of Ford Flex in our records for engine problems, this one ranks #2 by owner-complaint volume.
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.
Some 2009-2017 Expedition/Navigator, 2009-2014 F-150/Mustang, 2008-2009 Sable, 2008-2019 Taurus/Flex/MKT, 2013-2019 Police Interceptor Sedan/Utility, and 2011-2019 Explorer vehicles may exhibit inoperative or intermittent HVAC blower motor function at various fan speed settings. This may be due to a poor electrical connection at the blower motor speed control. If the blower motor speed control is determined to be the causal part, replacement of the electrical connector pigtail harness (14S411) to the blower motor speed control is also recommended to avoid repeat repairs. Refer to Wiring Diagram, Cell 5 for recommended splicing procedures. Refer to Wiring Diagram, Cells 54/55 to obtain the se
full bulletin at NHTSA ↗For 2010-2019 vehicles equipped with turbocharged engines, when diagnosing and/or replacing turbo related concerns, all steps within the Workshop Manual (WSM) procedure must be followed including replacement of all mandatory discarded parts. For all turbocharged engine applications, the turbocharger oil supply filter (6C683 gas engine/6L625 connector style or 6A968 diesel engine) must be replaced whenever the turbocharger or the turbocharger oil supply tube are replaced. Turbocharger bearing failure may occur if oil starvation occurs due to a restricted filter.
full bulletin at NHTSA ↗Some 2007-2016 Edge/MKX/Flex/MKT/MKZ/MKS/Taurus/Police Interceptor Sedan/Explorer/Police Interceptor Utility vehicles equipped with AWD and built on or before 30-Jun-2016 may exhibit a propane or natural gas odor during idle or low speed driving. This may be due to break down of the power transfer unit (PTU) fluid caused by excessive heat. If the source of the odor is identified as originating from the PTU, an idler bearing repair kit is available to repair the PTU. Refer to the Workshop Manual (WSM), Section 308-07. If the PTU is determined to be repairable, utilize kit GB5Z-7P258-A and the included instruction sheet. For claiming use causal part 7P258 and applicable labor operations in sec
full bulletin at NHTSA ↗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 ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2010 Ford Flex shows a pattern of serious engine defects across its lineup. The most severe and widespread is internal water pump failure. The water pump sits inside the timing chain cover, and when the seals fail—without warning—coolant floods the oil pan and crankcase, contaminating the oil. Owners report the engine suddenly shuts down at highway speeds, in traffic, or during turns, with loss of power steering and brakes. This has happened as early as 11,500 miles and as late as 192,000 miles. Coolant in oil has been confirmed by multiple Ford dealerships and independent mechanics. Owners face engine replacement bills of $4,100 to $8,000. Ford has not recalled the 2010 Flex for this defect despite issuing recalls on the same engine in other models.
EcoBoost 3.5L variants suffer repeated turbo failures traced to a faulty oil separator that floods the turbos with excess oil. Owners report replacing turbos five times within 2.5 years, with failures recurring monthly.
Beyond water pump failure, owners report unexplained engine stalls with no warning lights, often requiring multiple restart attempts. Piston ring failures at 55,000 and 103,000 miles cause complete compression loss. Cylinder misfire events and transmission slip into neutral at highway speeds add to the hazard list. One consistent report concerns exhaust fumes entering the cabin through malfunctioning pressure vents, recurring even after parts replacement.
Same Ford Flex engine reports on nearby years: 2009 · 2011 · 2013
Failure modes owners describe
Internal Water Pump Failure
The water pump, located inside the timing chain cover integrated with the engine block, leaks coolant directly into the oil pan and crankcase. This floods the oil with coolant, over-pressurizes the oil pan, and contaminates the lubricant. Many owners report catastrophic engine failure requiring full engine replacement.
When: Reported across wide mileage range: 11,500 miles to 192,000 miles; failures occur without warning during normal driving
Symptoms owners cite: Engine stalls or shuts down suddenly without warning lights in some cases; Temperature warning light and gauge pegging to hot; Strong smell of coolant; Loss of power steering and power brakes when engine dies; Check engine light illumination; Low power and sluggish acceleration before failure; Rough idle; Overheating
Codes mentioned: P0016
Repairs/costs cited: Engine replacement costs range from $4,100 to $8,000 reported by owners; coolant contaminating oil confirmed by mechanics; Ford dealerships have confirmed faulty internal water pump; repair bill estimates cited: $4,100 (used engine), $5,000 (full repair with labor), $7,800 (new engine at 55k miles), $8,000 (Ken Garff West Valley Ford)
Recalls/TSBs owners mention: Ford has not issued a recall for the 2010 Flex despite recalls on other models (2013-2015 Escape SUVs, 2014-2015 Fiesta ST, 2013-2014 Fusion, 2013-2015 Transit Connect); owners state Ford is unwilling to recognize the problem; vehicle out-of-warranty claims denied; NHTSA claims filed by owners with claim numbers 11792792 and CAS-11876774; Ford Customer Service aware but not providing coverage
Piston Ring Failure
Complete loss of compression in one or more cylinders due to piston ring failure, causing major power loss and requiring engine replacement. Occurs on regularly serviced vehicles.
When: Reported at 55,000 miles and 103,000 miles; one incident at 67,462 miles (cylinder 4 failure)
Symptoms owners cite: Sudden loss of power during acceleration; Engine shuddering or vibrating badly; Check engine light illumination; Cylinder compression test shows loss of compression in affected cylinder; Engine misfire in failed cylinder; White billowing smoke from exhaust (at 103k miles)
Codes mentioned: Cylinder misfire (specific cylinders 2, 3, 4 reported)
Repairs/costs cited: Complete engine replacement required; costs cited: $7,800 at 55,000 miles; oil was in good condition prior to failure; regularly serviced vehicles affected
Recalls/TSBs owners mention: Ford unwilling to help with repairs as vehicle out of warranty; no recalls issued
Turbocharger Failure (EcoBoost models)
Repeated turbocharger failures on EcoBoost 3.5L models, traced by owners to faulty oil separator that sends excess oil into turbos. Turbos fail multiple times within short timeframes, creating safety hazard with smoke and loss of power.
When: One owner replaced turbos 5 times within 1 year; another replaced turbos 5 times within 2.5 years; failures at 110,000 miles reported
Symptoms owners cite: Black smoke from exhaust pipes; Engine loss of power; Excessive smoke making vehicle undrivable; Turbo complete failure
Repairs/costs cited: Turbo and catalytic converter replacement; sensors replaced; one shop replaced turbos 5 times in one year; another owner replaced front and rear turbos within one month of each other; oil separator identified as root cause by Lincoln mechanic—faulty separator pushes too much oil into turbos causing them to fail
Recalls/TSBs owners mention: Parts reported unavailable at Hubler Ford (Shelbyville, Indiana); Pacifica Ford (Philadelphia, Pennsylvania) aware but failure recurred after repair
Sudden Engine Stall Without Warning
Engine stalls or shuts down suddenly during normal driving, often at low to moderate speeds, with little or no warning indicator. Multiple attempts to restart sometimes required. No diagnostic codes found in many cases.
When: Reported at 2,000 miles (brand new vehicle), 30 mph typical speed; incidents separated by weeks in some cases; also during acceleration, highway speeds (50-75 mph), and at stop signs
Symptoms owners cite: Engine stalls without warning; No warning lights prior to stall in many cases; Check engine light may or may not illuminate; Battery light illuminates in some cases; All dash lights illuminate in some cases; Loss of power steering and brakes; Gas accelerator becomes inoperable in one case; Vehicle difficult or impossible to restart immediately in some cases
Codes mentioned: No diagnostic codes retrievable in most cases
Repairs/costs cited: Dealerships unable to replicate or diagnose issue; one case: ignition coil replaced but did not resolve problem; throttle body replacement rumored to fix issue in some cases; one case: air filters cleaned; fuel and air sensors checked with no obvious defects found
Recalls/TSBs owners mention: Dealerships unable to diagnose; Ford engineer on-site could not find solution; dealers unable to perform repairs without vehicle demonstrating issue consistently; owners instructed to drive vehicle more to trigger problem
Cylinder Misfire and Power Loss
Cylinder misfire events causing sudden power loss, shaking, and engine shutdown. Fuel injector replacement attempted in at least one case but failure recurred.
When: Reported at 47,000 miles and 50 mph; 67,462 miles at 75 mph
Symptoms owners cite: Engine warning indicator illuminates; Violent vibration at highway speeds; Check engine light flashing; Sudden loss of power during acceleration; Engine misfires then dies
Codes mentioned: Misfire on cylinders 2 and 3, Cylinder 4 failure without compression
Repairs/costs cited: Fuel injector replacement attempted and replaced; repair did not resolve issue as misfire recurred at 50 mph on second occurrence
Recalls/TSBs owners mention: Ford notified; no recall issued; vehicle not repaired after second failure
Exhaust Fumes Entering Cabin
Pressure equalization vents behind rear bumper malfunction, allowing exhaust fumes to enter the vehicle cabin during acceleration, highway driving, or with windows open. Replacement parts available but issue persists across multiple vehicles with same problem.
When: Persistent issue across multiple visits; one vehicle serviced 8 times for exhaust repairs; recurs repeatedly
Symptoms owners cite: Exhaust fumes enter rear of vehicle during acceleration or highway speeds; Fumes enter with all windows open; Vents open when they should not due to improper pressure sensing
Repairs/costs cited: Two pressure equalization vents behind rear bumper identified; replacement parts procured but issue recurs; air conditioning and transmission also serviced on multiple occasions on same vehicle; third vehicle had similar issues across 8 service visits
Recalls/TSBs owners mention: Replacement parts available but recurring issue; Ford dealerships state this is a new problem with no known solution; multiple Ford Flex vehicles from same dealership exhibited same three recurring problems
Transmission Slip and Surge Events
Transmission randomly slips into neutral during acceleration and at highway speeds, with occasional engine surging at stops and hesitation at cruising speeds. Dangerous during stop-and-go driving and highway merging.
When: After three months of ownership; occurs during acceleration from stop, highway speeds (50+ mph), and at cruising speeds (45 mph to highway)
Symptoms owners cite: Random shift into neutral during acceleration; Neutral engagement at highway speeds (50+ mph); Engine surge at complete stop; Surge and hesitation at 45 mph to highway speeds; Cruise control disengages due to speed variance; Rapid deceleration before self-correction
Repairs/costs cited: Five repair attempts at Ford dealership unable to identify problem; dealership unable to determine cause
Recalls/TSBs owners mention: Dealership sent vehicle home until issue occurs consistently or vehicle breaks down; no repair attempted
Reduced Power and Hesitation on Acceleration
Engine bogs down during acceleration across various speeds with no trouble codes. Significant drop in fuel economy suggesting mechanical issue.
When: Persistent issue; not speed-specific
Symptoms owners cite: Vehicle bogs down during acceleration; Significant fuel economy loss: drop from 24 highway mpg to 14 highway mpg; Vehicle feels like it is fighting itself; No trouble codes present
Repairs/costs cited: Transfer case recently replaced; issue persists after repair
Synthesized from 29 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 5 most recent
While waiting at a light in my 2010 Ford flex the engine was idling rough, after the signal turned green the power seemed low and sluggish as I accelerated. When I was at about 45 MPH the engine power returned and seemed more normal, suddenly without notice the engine turned off and all dash lights illuminated. I was able to pull into a drive way but was very hard as there was no power steering.…
Tl* the contact owns a 2010 Ford flex. While driving approximately 60 MPH, the vehicle stalled. No warning indicators were illuminated. The vehicle was taken to a dealer where it was diagnosed that the engine air filters needed to be cleaned. The vehicle was not repaired. The manufacturer was not notified of this issue. The failure mileage was 52,843. The VIN was unavailable.
Piston rings failed at 103,000 miles. Total loss of compression and billowing white smoke produced from the exhaust. Always serviced regularly.
Heater blows cool air when in idle or parked. *tr
Engine stalls out, while driving the car around town. Has occurred twice, separated by a few weeks. No warning, or engine trouble or indicator lights prior or after the event. Occurs while driving a low to moderate speed both times, about 30 MPH. Car can be restarted immediately after and drives fine. Have had mechanics check fuel and air sensors and lines and find no obvious defects. Other…
Had engine trouble with your 2010 Ford Flex?
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 2010 Ford Flex?
It's a documented issue but not catastrophic. 29 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 26 complaints that reported odometer mileage, most engine failures cluster between 37,000 and 130,000 miles, with the median around 79,000. A quarter of owners report trouble before 37,000; a quarter make it past 130,000. 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/2010/Ford/Flex.
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.