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. …
2008 Mercury Mariner Hybrid was going 20mph on electric motor in traffic when triangle warning light came on and the stop safely now sign displayed. The vehicle gas engine did not come on and I had to pull over to the side. I place the car in park and turn off the engine. I restarted the engine and the warning light disappeared. I took it to the Ford dealership and they ran a diagnostic on it. They indicated it was the throttle body on the car that needs to be clean or replaced, and the PCM needs to be reprogrammed. I replaced it. This is after I took it to the Ford dealership to fix the two recalls for this vehicle - electric steering control and electric coolant pump for the Hybrid battery. I don't know if this will fixed the stalling issue since other vehicle owners indicated this problem persists, only time will tell. …
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.
The power torque sensor for the power steering was already recalled and had the system updated before I got the car in 2014. The cars steering wheel starts shaking a little then all of a suddle the steering wheel locks up and the power steering stops working, so you can't hardly turn it. I came inches from getting in a wreck. You can update the system but it will only work for about 1 or 2 years.
When decelerating down hill the brakes became seemed to have no power to stop the car and required extreme force to stop the car. Afterwards the electronic motor disengaged from the engine and the automobile runs on combustion engine only without the Hybrid electric motor assist.
Quits running while caution with explanation in middle light appears and wrench light appears. Then notification to stop at once safely. This has happened on freeway. After 15-20 minutes car will crank again but May only go a few feet and stall again, near death experience.
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 ? …
I was traveling west at about 70 MPH in the left lane on I-66 out of washington, dc with four people in the car. Suddenly, the engine died and we were left with only the electric motor on the Hybrid and a dash warning of a red triangle and the statement "stop safely soon." the car quickly lost power to about 30 MPH and we struggled to get across the four lanes to the shoulder. The electronics in the car still operated (radio, dash lights, etc.), but the gas engine stalled. Once on the shoulder, we stopped. The Ford owner's manual told us to turn the car off and try to re-start. We did this and the car re-started. We started to drive, but the car did the same thing after about 5 minutes. The car did the same thing on about 5 different occasions until we could get to an exit that had businesses. …
While traveling down the interstate at approximately 70 MPH on a Friday evening a red triangle shaped warning light came on saying "stop safely now", as the light came on the vehicle started loosing power going slower and slower, eventually slowing to 20 or 30 miles an hour, there was no safe place to pull over off the interstate. This was not safe at all. After pulling over, then pressing system reset buttons, turning off the vehicle and waiting a few minutes then restarting the vehicle it ran fine for the rest of the day and the following day. Then on Sunday (a day and a half later) I was traveling down the interstate and it did the same thing, the light came on and I lost power. I repeated what I did the previous time, but it did it again while on the interstate, it did it several times. …
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. …
NHTSA investigations
Pedestrian alert sounds
NHTSA received a petition on or about July 18, 2022, requesting that Federal Motor Vehicle Safety Standard (FMVSS) 141 be applied to all electric and hybrid vehicles operating in the United States. The petition can be reviewed at NHTSA.gov under ODI Number 11486072. FMVSS 141 establishes performance requirements for pedestrian alert sounds for motor vehicles.
Electrical complaints in other Mariner Hybrid years
Frequently asked questions
How common are electrical problems on the 2008 Mercury Mariner Hybrid?
NHTSA has 22 complaints about the electrical system of the 2008 Mercury Mariner Hybrid, 19% of the model year's 116 complaints.
Is there a recall for 2008 Mercury Mariner Hybrid electrical problems?
No. NHTSA lists no electrical 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 electrical problems start?
Half of the complaints with a recorded mileage happened before about 67,000 miles, and 10% 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.