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 2009 Mercury Mariner Hybrid
2009 Mercury Mariner Hybrid
2009 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.
The Check Engine Light may illuminate with code P0442, P0456, and/or P1450. These codes are related to the EVAP system. Our technicians tell us that if no EVAP system faults are confirmed, updated software is available for the powertrain control module (PCM) which should correct this concern.
2009 Mercury Mariner Hybrid Questions and Answers
2009 Mercury Mariner Hybrid Reviews
I traded in a 2000 Chev Tahoe LT for my 2009 Mercury Mariner I has more pick up when geting on the freeway smaller easy to drive the in cabin lighting is great the hybrid engine works fine. My only complaint is the engine noise is a little louder then I would like. The navigation & sync system are great all and all I really like the Hybrid mercury Mariner. I'm getting 34-36 MPG