I serviced my 04 Nissan Pathfinder and noticed that the "service engine soon" light came up shortly ther after. A day later, the car overheated while in slow moving traffic. The mechanic came over to remove the thermostat. Of course, the car overheated again the following day, I was lucky I already got to a convenient spot in my itinerary. i waited for it to cool down. The level of water in the radiator did not go down, and i was able to take it from ibadan to osogbo and back to Lagos - a distance of over 200Km. I think removing the thermostat was rather crude becuase the thermostat has been there since almost 10 months ago that I started using the car in naija. Secondly, the car came from Houston, which can be as hot as naija, so I really do not think removing the thermostat was going to solve any problem in the first place.

Please what can be wrong with the car? What can I do? Abeg help me o.

@poster, why dont u look for a certifield mechanic to check it for u

From my little experience. . . . no one removes thermostats from cars nowadays particularly cars that are recently made,  Get it fixed back if possible and take it to certified mechanic workshop so they can read what is wrong with the car. . . Peace Bro!

Get a Stant thermostat and you'll probably need a new waterpump.

what's a "Stant Thermostat"? I thought a faulty water pump should make the water level in the radiator reduce every now and then. Abi?

A thermostat made by a company called Stant, reputed to be very good, and if it fails , it stays open.http://www.stant.com/
If your water pump is bad, water will not circulate between engine block and radiator.SO water in engine block stays hot, and radiator stays warm/cold.

But water pump only applies if radiator is colder than engine temp(by feeling the hoses), now if they are both hot, your cooling fan is not working(I hope you had checked this first) Also check to make sure all your belts are in place(properly routed) by checking diagram on hood.

Lastly radiator cap.