There are 1 owner-reported powertrain & transmission complaints for the 2009 Mercury Grand Marquisin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
MY WIFE WAS DRIVING AROUND 25 MPH AND LESS THAN ONE MILE FROM OUR HOUSE. WHEN SHE APPLIED THE BRAKES TO STOP AT A STOP SIGN THE ENGINE REVVED UP. I WAS RIDING WITH HER AND OBSERVED THE ENGINE REV TO AROUND 2,500 RPM BEFORE SLOWING DOWN. I ALSO OBSERVED THAT HER RIGHT FOOT WAS ON THE BRAKE AND THAT NOTHING WAS TOUCHING THE ACCELERATOR. THE CRUISE CONTROL HAD NOT BEEN TURNED ON. THIS WAS AT LEAST THE FOURTH TIME THIS YEAR THAT THE ENGINE REVVED UP WHEN THE BRAKES WERE APPLIED. THE DEALER COULD NOT FIND THE PROBLEM AND THE ENGINE DID NOT REV WHILE THE DEALER WAS TESTING THE CAR. *TR
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 26, 2026