Which parts fail
Components named in complaints (fuel pump, injectors, fuel tank, hybrid and EV propulsion).
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. …
Returning from florida to georgia and passed a vehicle at about 70mph and released the accelerator but vehicle kept accelerating. I pressed the brake pedal but vehicle kept accelerating. I pressed the accelerator again and vehicle finally stopped accelerating. Additionally, "stop safely now" message intermittently occurs at highway speeds and around town in traffic and slows the vehicle to perhaps 10-15mph and tells me to pull over. This has happened randomly at unspecific times and in heavy traffic which could be dangerous. I have concerns that this issue needs to be a recall from Ford since a lot of people are having the issue from forums online and it could result in wrecks and maybe even fatalities.
Tl* the contact owns a 2008 Mercury Mariner Hybrid. The contact stated that the stop safety now warning message illuminated and an unknown warning light illuminated. The contact mentioned that when the defroster was activated, the warning lights no longer illuminated. The vehicle was not diagnosed or repaired. The vehicle was not included in NHTSA campaign number: 14V526000 (Hybrid propulsion system). The vehicle was included in NHTSA campaign number: 14V284000 (steering). The dealer was unable to confirm when the parts would become available to schedule the recall repair. The manufacturer was notified of the failure. The approximate failure mileage was 100,000.
Tl* the contact owns a 2008 Mercury Mariner Hybrid. The contact stated that while parked, the ignition switch did not move from the off to on position without warning. The failure recurred on numerous occasions. The vehicle was taken to the dealer where it was diagnosed that the coolant pump needed to be updated and repaired. The vehicle was not repaired. The manufacturer was made aware of the failure and stated that the VIN was not included in NHTSA campaign number: 14V526000 (Hybrid propulsion system). The approximate failure mileage was 199,000. The VIN was not available.
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.
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 ? …
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. …
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. …
We bought vehicle in jan, 2018 from a private party, as a work vehicle for my husband, who is a usps rural route carrier. Two weeks after purchase, the anti-lock brake light went on, and the car would not stop when it was supposed to, which was very dangerous in winter. We believe the prior owner knew about this. The light would just go on & off with no pattern. About 1 1/2 months later, he was driving on a 2 lane hgwy (55 MPH) delivering mail. He went to pull forward but the car made a brief noise and then everything just stopped working. The car wouldn't start, no electrical or lights, he could not even roll the vehicle by himself to a safe place w/out help. The electrical and propulsion simply stopped working; period. We ended up dragging it home. Dealership gave est. Amt of repairs around $18K. I found the recall in 2014 (14s19) for the same thing. …
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. …
Fuel System complaints in other Mariner Hybrid years
Frequently asked questions
How common are fuel system problems on the 2008 Mercury Mariner Hybrid?
NHTSA has 20 complaints about the fuel & propulsion system of the 2008 Mercury Mariner Hybrid, 17% of the model year's 116 complaints. The component named most often is inverter (1 mentions).
Is there a recall for 2008 Mercury Mariner Hybrid fuel system problems?
No. NHTSA lists no fuel & propulsion system 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 fuel system problems start?
Half of the complaints with a recorded mileage happened before about 67,000 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.