Some Mercury Mountaineer owners report experiencing issues with spark plugs blowing out, leading to engine misfires and damage to coil packs. Common symptoms of faulty spark plugs include poor acceleration, rough idle, and a check engine light, while bad ignition coils can cause engine hesitation and excessive fuel consumption. Additionally, trouble code P0302 indicates a serious misfire in the second cylinder, which requires prompt attention. If the problems persist after replacing spark plugs and coils, owners may need to investigate other potential causes such as a faulty crankshaft position sensor or fuel-related issues. Furthermore, a random misfire indicated by trouble code P0300 suggests that the Engine Control Module is unable to identify the exact source of the misfire, complicating the diagnosis. Addressing these issues is crucial for maintaining proper engine performance and preventing further damage.

A coolant leak may develop from the radiator. Ford has released and updated radiator and powertrain control module (PCM) software update to address this issue. The software update includes revised cooling fan operating parameters. Failure to complete both service procedures may result in repeated radiator failures.