Q: Truck runs really rough, smells like antifreeze in the cabin, testing said it was O2 sensor, and there is an overheating, hissing noise

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Runs rough, testing said o2 sensor, but , which one? cabin smells like antifreeze, also overheated for the first time, there is some kind of hissing on the passenger side, like a hose? But can't find out where? And the last 2 days the heat won't get warm? Thermostat or could it be o2? Or both?

My car has 193000 miles.
My car has an automatic transmission.

Hello. You can possibly rent a cooling system pressure tester from a local chain auto parts store. With the engine off, remove the radiator cap and pump the cooling system to no more than 10 psi. You will be able to search around the engine compartment and find where the coolant is coming out. You stated that, "Testing said O2 sensor," if this was found out with a scan tool, then it should indicate that there is something wrong with O2 sensor and the sensor will either need to be replaced or the circuit checked for any faults. If you need further diagnosis of the rough running to verify the fault, a certified professional from YourMechanic can come to your home or office to inspect the car and proceed with repairs.

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