The firewall on your 1999 Mercury Grand Marquis is the metal wall that divides the passenger compartment from the engine compartment
One of your door sensors needs to be replaced.
99 G/M has no filter.
For a 1999 Mercury Grand Marquis : ( 15 city / 22 highway miles per U.S. gallon ) according to a website I was looking at
For a 1999 Mercury Grand Marquis : ( 15 city / 22 highway ) miles per U.S. gallon , according to a website I was looking at
On a 1999 Mercury Grand Marquis : In the fuse panel below and to the left of the steering wheel , by the brake pedal ( it has a cover on it ) ( # 16 is a 20 amp fuse for the cigar lighter )
Not with out raising the marqui. The bigest you can go with out any problems will 20'' www.twtireandrims.com
No
In the gas tank.
Means that the o2 sensors have detected that the catalytic converter is not handling the emissions of the engine for some reason. Diagnose, don't guess as the parts can be expensive.
The relay for a 99 Grand Marquis heater is located on the kick panel on the driver's side of the car. The relay is located under the kick panel cover.
In a 1999 Mercury Grand Marquis, the fuse for the dome light is located in the fuse box, which is typically found under the dashboard on the driver's side. Specifically, it is usually labeled as "Dome" or "Interior Lights." Check the owner's manual for the exact location and fuse number for reference. If the dome light is not functioning, inspecting this fuse is a good first step.