Pacifica Coolant Mystery: Hidden Leaks Cause Overheating

I faced a similar issue with my 2011 Chrysler Town & Country last summer. Having some experience with cooling systems, I recognized the symptoms you described and had them checked out right away. The problem turned out to be a faulty sensor connector near the coolant reservoir that was giving incorrect readings to the ECU. The connection had corroded over time, causing intermittent signals about coolant levels and temperature. After testing the system, my mechanic found no actual leaks in the radiator hoses or head gasket, which was a relief. The repair was relatively straightforward, cleaning and replacing the connector assembly cost 95€ and took about an hour. Since then, the engine overheating warnings stopped and everything has been running normally. To better assist with your situation, could you share: Current mileage on your Pacifica, Whether the overheating occurs more during idle or highway driving, If you notice any sweet smell from the engine bay, When was your last coolant system service This information would help determine if you are dealing with a similar electrical issue or potentially something more serious with the cooling system components.

Thanks for the helpful reply. My Pacifica has 29802 KM and last service was 2 months ago. The overheating mostly happens during city driving and gets worse in traffic. Never noticed any sweet smell, but there are air pockets forming in the radiator fluid after driving. The cooling fan seems to run constantly when the engine is hot. I checked yesterday and noticed some wetness around the radiator cap area, though its hard to tell if its an actual leak. The coolant level drops gradually over a few days after refilling. Going to get it checked this week, hoping its just the cap or sensor like in your case and not something major with the water pump.

Thanks for the additional details. Based on what you described, your symptoms are quite different from what I experienced with my Town & Country. The constant cooling fan operation and air pockets point toward a more significant issue than just a sensor problem. The wetness around the radiator cap combined with gradual coolant loss strongly suggests a pressurization issue in the cooling system. When I had my sensor fixed, I didnt have any visible moisture or air pockets forming in the system. A failing radiator cap can cause these symptoms, but given that your coolant reservoir level keeps dropping, you might be dealing with: A small crack in the radiator, A failing water pump seal, A compromised head gasket The repair costs can range from 25€ for a new radiator cap to 800€ or more for a water pump replacement. Since you mentioned the cooling fan runs constantly, have the mechanic check the temperature sensor as well, a faulty sensor could cause the fan to run unnecessarily. I would recommend getting a pressure test done on the cooling system. This will pinpoint any leaks and save you from replacing parts unnecessarily, which is what helped diagnose my sensor issue correctly.

The wetness near the radiator cap and air pockets in the coolant system definitely have me concerned. Thanks for explaining the potential causes, I was hoping it would just be the cap, but the constant coolant loss makes me think its probably the water pump. I scheduled a pressure test for tomorrow morning. Will have them check all the cooling system components, including the temperature sensor since the fan issue seems unusual. Really hoping to avoid major repairs, but at least now I know what price range to expect, anywhere from 25€ for a simple cap to 800€ if the water pump needs replacement. Appreciate everyone sharing their experiences. Will update once I get the test results and know exactly what needs fixing. Just crossing my fingers its not a head gasket issue, since that would be much more expensive than a standard cooling system repair.