Question

2000 Mercury Grand Marquis 4.6L with engine code P0125, insufficient coolant. How can I fix this problem?

Answer 1

P0125 Insufficient coolant temperature for closed-loop fuel control

Check the coolant level, another cause for this code is a thermostat that malfunctions where it is stuck open

 

Here a thermostat that got stuck open can cause P0125. When the thermostat is stuck open there is not much drive ability problem the vehicle just uses more fuel. and in this case, you replace the thermostat

Here is another P0125, this leak was from the intake manifold, it caused a P0125 this vehicle was low on coolant, unfortunately, the vehicle overheated, what was a simple intake manifold gasket replacement is now a cylinder head that needs to be replaced.