2000 Nissan Altima temperature gauge and heater problem

This could be one of a few options.#1 could be as little as 1 quart to one half gallon low on coolant in radiator; #2 could be thermostat may be stuck in Open position all the time ( check temp gauge to see if engine is at Normal operating temperature ) #3 could also be stopped up Heater Core....Check this by simply touching heater hose going into heater core and heater hose exiting heater core, at any rate if the core isn't stopped up, Both hoses Should be warm or hot at regular operating temperature of engine warmed up.

thermostat is stuck open. or you have an air pocket in the cooling system or the bypass door is stuck in the wrong position.

Heater core may be clogged. Try flushing it to see if water flows through freely. Also check the heater water control valve for restrictions.

make sure you have plenty fluid in the radiator and the bottle. sounds like it is low.

The blend door may be malfunctioning if the heater core gets hot enough to heat at any given time.

First thing is the that the coolant temperature sensor is quite different to the temperature sender that is monitored on your dash board. Assuming everything is working fine the thermostat may be stuck open. This would cause coolant to be circulated without restriction and so remaining cooler than usual even when the engine is at running temperature.

Hi Code P 0217 does point to the thermostat but it also points to the wiring, cooling system, and the temperature sensor, to check the thermostat start engine then once the temperature gauge in the car reaches normal the thermostat should open and the top hose that goes into the radiator will warm up quickly as the thermostat opens, if the thermostat is stuck in it's open position the top hose will start warming up before the engine reaches it's working temperature, hopefully i have explained it clearly,

Try replacing the thermostat. Sometimes they can create a problem like this when they are not opening and closing at the proper temp.

Hi!
It appears we have an Air lock scenario and you will need to perform a system Bleed.
Park the vehicle on level ground, when cold remove coolant filler cap, start engine and leave to idle, turn heater on full and blower to max. When engine reaches operating temperature watch and listen near coolant filler, keep clear as gurgling and hopefully a boil over should occur. Top up with very warm coolant and wait as it may do it again.
Check for heat inside vehicle if warm replace coolant cap but keep an eye on temperature gauge as the ~Air lock may have moved on from heater matrix/core so proceedure needs to be carried out again from COLD.

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Paul 'W' U.K

My 2005 Nissan Sentra 1.8s with 55,000 mi. blows cold air from the heater. Coolant not circulating in engine. Lower hose stays cool to touch. Both heater hoses cold. Changed thermostat - didn't fix it. Coolant not leaking or dirty. None in oil - no oil in radiator. Changed worn water pump belt - pump spins freely with no noise or resistance. Cooling fans come on after warm-up. Temperature gauge stays in normal range then jumps to hot and back again. Coolant good to 10 below - didn't freeze here yet. No other problems or repairs to car. Afraid to drive and make worse. Help!