Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2008 Mercury Mariner Hybrid owners, lightly cleaned up (personal details are redacted by NHTSA).
Experienced two in-traffic drive-train shut-downs as dangerous as the g.m. Ignition switch malfunctions... Traveling in 60mph-70mph night-time valentine's night freeway traffic on the I-405 in santa ana, ca. In the #3 lane of 5 lanes, the check engine warning light suddenly flashed on - accompanied by the `screech' of the `check gauges' tone - and the drive-train lost all power -- along with the absolutely worthless text "stop safely now". With no power steering, and limited brake booster reserves, I activated the hazard flashers - and thanks to alert and courteous traffic, was able to stop in a "reverse gore-point" between the freeway lanes and an outside transition road. Things could have come out far-worse if overtaking drivers had been inattentive - or we had to cross the path of a big-rig with limited braking- or steering capabilities. …
Tl* the contact owns a 2008 Mercury Mariner Hybrid. While driving at 60 MPH, the vehicle stalled and the check engine warning light illuminated. The contact was able to restart the vehicle; however, the failure recurred. The vehicle was taken to a dealer where it was diagnosed that the coolant pump needed to be replaced. The vehicle was repaired. The vehicle was previously repaired under NHTSA campaign number: 14V526000 (Hybrid propulsion system). The manufacturer was not notified of the failure. The approximate failure mileage was 70,000.
Stop safely now chimes and displayed on dash followed by no acceleration until vehicle stalls and stops.starts right back up but continues to happen especially in la rush hour traffic. Very dangerous! Had recall work done on the mecs 3yrs ago but problem has continued. This happens while in motion on the 110 freeway in downtown los angleles, ca. Could be the electric throttle body or rear actuator. Or any other component that works with the electric motor and battery.
Tl* the contact owns a 2008 Mercury Mariner Hybrid. The contact stated that while driving at various speeds, the vehicle loss motive power and stalled with an unknown warning light illuminated. The vehicle was taken to andy mohr Ford located at 2713 e. Main st, plainfield, in 46168 however, the vehicle was not diagnosed nor repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 87,000.
This would be the second un-warned total loss of power on a freeway. Having coasted out of traffic on the first unwarned engine / propulsion system shut-down in fast-moving freeway traffic, managed to find wide-enough section of outside shoulder to come to a stop. But being stuck in 10 pm darkness on a narrow shoulder was too dangerous to consider remaining there. Once stopped, I shifted the transmission to park, cycled ignition off then to start ? Engine restarted, dash warning lamps came on- then cycled off normally, engine ran smoothly. Note: the only way to attempt to restart the Hybrid drivetrain is to shift the transmission into park .. It doesn't work in neutral .. And there was no way I was going to try to put the trans in park in 72-75 MPH freeway traffic in 10 pm darkness. Accelerated moderately into merging lane, entering gap in n/b traffic to re-enter I-5 traffic ? …
Traveling down the interstate, left lane @ 70 MPH. I had 1 vehicle behind me and a semi truck / trailer to the right and one behind him. Without warning the engine died and I began coasting in traffic. I hit my flashers and thankfully the vehicle behind me was alert and noticed my instant loss of speed and flashers. They slowed long enough for both big trucks to pass on my right and for me to get over to the shoulder on I-70. Quick research turns up possible issues with a mechanical / electrical pump or maybe the throttle body. I called the Ford dealership and talked to the service manager who didn't have a clue what would cause the issue and was surprised that I found several postings on the internet where people had the same issue in the same model vehicle. …
Experienced the second of two in-traffic drive-train shut-downs as dangerous as the g.m. Ignition switch malfunctions (see odi#: 10683675) our initial stopping place - in a "reverse gore-point" between the n/b freeway lanes of the I-405 freeway in santa ana, ca and an outside transition road was unsafe in the full-darkness of a non-illuminated high-speed intersection; with traffic zooming by on both sides, with the flashers still active, I res-started the engine -- all dash warnings cycled on then off normally; on a distinct up-grade, I revv'd the engine against the service brakes, and watched for a suitable gap in traffic over-taking us on our right side. …
Stalling, total loss of power on freeway, or making a city turn, or accelerating from a stop sign or light, or going up even a slight incline, such as a driveway to a house. Only in the summer. Do not dare use air conditioning, which makes it occur quicker and much more often. 95 degrees outside, 113 degrees in car - cannot and do not use air conditioner, but still happens on trip over 15 minutes long. Totally unsafe. Like other contributors, I would like to know why there has been no recall. Just today, July 10, 2013, 18-wheeler behind me (close) on 45 MPH city street, and I stalled. I stuck my left hand out of my window in a "please stop" gesture, and driver did stop, but I was terrified. Must come to full stop, put car in park to re-start it. But same thing will happen at next light or sign or change of speed, whether in 5 minutes or 30 seconds, city street or freeway. …
Driving in fast lane of freeway when "stop safely now" message with red alert came on. The engine stopped running. No warning, no ability to drive to the side of the road. This is a known fault in this vehicle. I cannot conceive of a problem that would require the engine to stop immediately. It is just luck that we got to the side of the road without incident as there was a lot of traffic, and without power, it was just plain luck that we managed to get to the side of the road. Doing internet research: this is a known fault, but without a solution or a fix. What ever the problem, it seems ridiculous that Ford has a major problem like this that has the engine simply stop. We got to the side of the road. I simply turned off the ignition and re-started the engine, without further problem. …
This has occurred twice. The first time, (9-6-2010), driving in bumper-to-bumper traffic on the freeway- the light, "stop safely now" comes on and you cannot use the gas pedal and you have to try to get to the shoulder safely as the car has no power. I waited for half an hour and restarted the car and was able to get to where I had to go. Took it to dealer and they couldn't find anything wrong with it. The 2nd occurrence (March 31, 2012), same thing happened except I was on the freeway with everyone going at least 65 miles per hour and had to get to the shoulder without any power. Took it to dealer and they said it was a coolant pump problem. I went online and there are hundreds of complaints about this problem. This should be a recall issue and I shouldn't have had to pay for this. Extremely dangerous. Could so easily have been hit by oncoming traffic. Scary experiences.
Engine complaints in other Mariner Hybrid years
Frequently asked questions
How common are engine problems on the 2008 Mercury Mariner Hybrid?
NHTSA has 40 complaints about the engine & cooling of the 2008 Mercury Mariner Hybrid, 34% of the model year's 116 complaints. The component named most often is engine (4 mentions).
Is there a recall for 2008 Mercury Mariner Hybrid engine problems?
No. NHTSA lists no engine & cooling recall for the 2008 Mercury Mariner Hybrid. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2008 Mercury Mariner Hybrid engine problems start?
Half of the complaints with a recorded mileage happened before about 67,000 miles, and 3% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.