Possible Causes:
* Low Coolant: This is the most likely culprit. The system might be low due to a leak (hose, radiator, water pump) or a head gasket failure (more serious). Check your coolant level in the overflow reservoir – but be extremely careful as the system may be under pressure and very hot. Let it cool completely before checking.
* Faulty Water Pump: A failing water pump can't circulate coolant effectively, leading to overheating.
* Thermostat Stuck Closed: A stuck thermostat prevents coolant from circulating until a certain temperature is reached, leading to overheating.
* Radiator Problems: A clogged radiator or a leak in the radiator itself will hinder efficient cooling.
* Head Gasket Failure: This is a more serious issue. A blown head gasket can allow coolant to leak into the engine or vice versa, resulting in overheating and potentially contaminating the engine oil. This is indicated by white smoke from the exhaust, milky oil, or coolant in the oil.
* Faulty Cooling Fan: The cooling fan might not be working properly, failing to draw enough air across the radiator.
* Sensor Issues: While less likely to be the primary cause given the other symptoms, a faulty coolant temperature sensor could give inaccurate readings, leading to the warning lights.
What to Do:
1. Safety First: Do NOT drive the car until you've addressed the overheating issue. Continuing to drive with an overheating engine can cause severe and costly damage.
2. Cool Down Completely: Allow the engine to cool down completely before attempting any inspection or repair.
3. Check Coolant Level (Carefully!): As mentioned before, check the coolant level in the overflow reservoir after the engine has cooled. If it's low, this is a very strong indicator of a leak.
4. Inspect for Leaks: Carefully examine all hoses, the radiator, the water pump, and connections for any signs of leaks (wet spots, corrosion, etc.).
5. Get it Diagnosed: It's highly recommended you take your Mercury Marquis to a qualified mechanic for a proper diagnosis. They have the tools and expertise to identify the precise cause of the problem and make the necessary repairs safely and efficiently. Ignoring this could lead to significant engine damage.
6. Obtain and Read OBD-II Codes: A mechanic will have a scanner to read the check engine light codes. This provides further clues about the problem. Some auto parts stores will read the codes for free.
The combination of warning lights and the gauge behavior points towards a serious cooling system problem. Do not delay in getting it checked by a mechanic.
