Report: Check Engine Light and/or Engine Overheating
BMW 525i Problem
The thermostat may fail resulting in engine overheating and/or illumination of the Check Engine Light. Replacement of the thermostat along with a complete inspection of the cooling system will be necessary to correct this concern.
Overheating can cause severe engine damage. If the engine begins to overheat it is recommended to stop at the first available location and have your vehicle towed to a repair shop.
Visitor, 2002 BMW 525i, 150,000 mi
My coolant thermostat became stuck open, resulting in the service engine soon light coming on, but now resulting in any overheating of the engine. My belief is that the coolant is always being put into the engine and the valve of the thermostat is just stuck so it will not close when the engine is off or cool enough to run efficiently. I need to replace the thermostat, but I don't believe the housing itself will need to be replaced as it is still in good condition and has no cracks or issues.