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.
Resources for the Repair and Maintenance of your 2008 Mercury Mariner Hybrid
2008 Mercury Mariner Hybrid
2008 Mercury Mariner Hybrid Problems
Hard driving conditions, including quick starts from a stop and hard acceleration up hills, can cause the rear motor mount to crack. The broken motor mount needs to be replaced, otherwise damage to the hybrid drive system may result.
2008 Mercury Mariner Hybrid Questions and Answers
So I have recently been having a lot of problems with my car. About a year ago my radio/navigation screen wouldnt work every now and again. My car was still running & I was fully able to driv...
2008 Mercury Mariner Hybrid Reviews
The break issue posted above is caused by a faulty speed sensor in the cruise control. Mine was under warranty, but it took them maybe 30 minutes. I had this, and the real tailgate release break. Otherwise no tires, no repairs nothing for 110K miles. It is a great car.
My 2008 Mariner 2WD had to have the computer replaced at about 38,000 miles. It's failure caused the car to quit running on the highway, very dangerious. The good news was the hybrid feature allowed me to get to a dealer and it was covered by the 60,000 mile powertrain warrenty. Now at 59,000 mile the AC compressor failed and had to be replaced (not warrenteed) to the tune of $1,100.00. I am very dissapointed having had many cars with greater milage and not had to replace a major AC component. Has anyone else had a problem like this?
I've had issues with the brake system on this car. I get check brakes warning lights regularly but nobody can find a problem. Sometimes the brakes grab sometime they feel soft and it changes from mile to mile. I've had to replace the brake pump and master cylinder which cost me $1400 for a different break issue. It was expensive because these are designed as one part. But the current problem was not resolved by this.
Otherwise I am very satisfied with the car. Great mileage, good comfort and handling. All you could ask for in a small SUV.