Car Problem Reports

Mercury Mariner Hybrid Coolant Pump on Hybrid May Fail and Cause CEL/Engine Shutdown

Mercury Mariner Hybrid Problem
49 Reports
Me Too

Model Years Affected: 2006, 2007, 2008, 2009, 2010

Average Mileage: 96,691 mi (36,700 mi - 185,000 mi)


The hybrid models have a coolant pump that cools control electronics. The pump can fail or spin slowly, which causes a Check Engine Light to illuminate and complete engine shut down.

  •  Rookie

    Having the same problem. What I don't understand is why is it not giving me a wrench to tell me something is wrong. In fact, it is saying the opposite, that everything is working fine and as it should. I had cruise control on, it happened about 50 miles from home. Just surged a bit, then completely shut down and gave me the PULL OVER SAFELY NOW message. Each time it happened I stopped and shut it off and restarted it and it never gave me any indication there was a problem until I got back on the highway and it happened again. and again. I had it towed to a dealer where it is now.

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  • , , 90,444 mi

    Coolant pump went out. Same issue with sudden shutdown and needing to pull over for a while. Repair was $560 including a new bracket. The only problem I have ever had with 90k miles. I read this website before going to dealer, told them it was likely the coolant pump, and their diagnosis was exactly the same. Thanks!

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  • , , 78,000 mi

    car completely shuts down while driving...have to pull over and restart...will go for awhile and then have to keep doing this...we thought we had bought bad gas

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  • , , 103,000 mi

    Same as previous, Shut down on interstate with limited exits available. Very scary as we were a long way from home. Recall should take place, very dangerous if in the wrong place when it shuts down. We had just purchased the vehicle, so we had anther car following, A 2 hour rip took 9hrs and ended up driving home in the Prius to get truck and trailer to retrieve it on , arriving at 11:15 pm. This msgboard has been a big help, will also follow up with Ford

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  • , , 108,000 mi

    Was driving on freeway, engine shut off with alert to "Pull Over Safely Now". Was able to restart the vehicle, but it shut off again. Had it towed to a Ford dealership and confirmed it was the hybrid mechanical pump for cooling the hybrid system.

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  • , , 75,900 mi

    Thanks to all of you sharing your experiences. I too was having my vehicle shut off while driving. Would pull over and wait a couple of minutes and back on the road I was. Two minutes later it shuts off and tells me to pull over safely. No wrench or anything telling what the problem is. I too had it towed but to my house. The next day the wife used with no problems for the next two days. I then drove it and off it goes again. Made it home and left it alone. Got on this web site and read that the same problem occurred with my car. I bought the Coolant pump myself and replaced it ($182.00). Problem solved...for now.

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  • , , 92,000 mi

    This same problem happened to my 2007 hybrid. Check engine light came on and engine quit. After pulling over the car was able to restart. We did this on backroads continually for our 80 mile drive home, the car ran a little less time after each restart. The coolant pump was replaced - I'm thinking it was in the $400 range.

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  • , , 107,500 mi

    My mercury mariner hybrid stalls on the interstate. Just prior to the stall, the vehicle seems to lunge forward slightly, then the engine quits. We have to pull over and restart. One day this happened to me twice, within a few hours apart of each other.

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  • , , 90,000 mi

    Engine shutdown suddenly on interstate at 70 mph. VERY dangerous and scary. Dealer replaced fan, but I was on vacation and the wait for parts and service used up time I had planned for other things. Other than this problem, vehicle has been reliable.

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  • , , 96,000 mi

    this is the second time in less than a year . shuts engine down not safe on highways should have been a recall they all do it .what makes this coolant pump fail

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