Engine

COMMON PROBLEMS: Coolant Intrusion (EcoBoost), Carbon Buildup, Timing Chain and Cover Leaks, Oil Leaks, Spark Plug and Coil Wear

The EcoBoost engines are the ones to know here. Some are prone to coolant intrusion, where coolant works its way into a cylinder and burns off with no puddle to show for it, so the level just keeps dropping. Direct injection also cakes carbon onto the intake valves over the miles, which dulls the throttle. The timing chain area and the front cover can seep oil as the seals age, and worn plugs and coils bring on misfires. Different engines, different weak spots, which is why the first job is knowing yours.

Cooling System

COMMON PROBLEMS: Water Pump Failure, Coolant Loss, Overheating, Thermostat Failure, Hose and Radiator Leaks

The water pump is the headline on a lot of Explorers, and on the ones where it's driven internally by the timing chain, a failure turns into a deep, expensive job. That's the reason catching an early seep matters so much here. Beyond the pump, hoses crack, the radiator can split at a seam, and a stuck thermostat sends the temperature the wrong way. Summer traffic and towing are when a marginal system tips over. Run one hot and you're risking a warped head, so a small coolant problem is not one to sit on.

Transmission

COMMON PROBLEMS: Rough or Delayed Shifts, Shudder, Slipping, Overheating While Towing, Transmission Codes

The Explorer's automatic can get rough as it ages and the fluid wears, and that's where a lot of complaints land. A shift that jerks instead of glides. A hesitation between dropping it in gear and the truck moving. A shudder at a steady cruise. Towing and stop-and-go heat the fluid and speed all of it up. The cheap thing to rule out first is fluid level and condition, since a service sometimes settles it. If a solenoid or something deeper inside is behind it, the codes usually point the way.

Electrical System

COMMON PROBLEMS: Battery Drain, SYNC Screen Glitches, Sensor Faults, Warning Lights, Starting Problems

There's a lot going on electrically in a modern Explorer, and any of it can act up. A flat battery in the driveway usually means something stayed on and drained it overnight. The SYNC touchscreen has its moments, freezing or rebooting on its own. A sensor can throw a fault and light the dash or drop the truck into a limp mode with no obvious cause. Some of it is a tired battery or a corroded ground. Some of it is a module or wiring problem that takes real testing to pin down.