Jetta 2003 temperature gauge not working...

There could be a few different issues that could cause the temperature gauge on your 2008 Ford Focus to read hot when the engine is not actually overheating. Here are a few things to consider:

Failed thermostat: The thermostat is responsible for regulating the flow of coolant through the engine. If the thermostat is stuck in the closed position, it could cause the temperature gauge to read hot even though the engine is not overheating.

Failed temperature sensor: The temperature sensor sends a signal to the temperature gauge to indicate the engine's temperature. If the temperature sensor is faulty, it could cause the temperature gauge to read hot even though the engine is not overheating.

Wiring issue: If there is a problem with the wiring that connects the temperature sensor to the temperature gauge, it could cause the gauge to read hot even though the engine is not overheating.

To determine the cause of the issue, it may be necessary to perform some diagnostic tests and possibly replace some components. A mechanic or a professional auto repair shop will be able to diagnose the problem and recommend the appropriate repairs. It's also a good idea to keep an eye on the engine temperature and take note of any other symptoms or issues you may be experiencing. This information can help the mechanic diagnose the problem more accurately

Reasons the Temperature Gauge Reads High

If the temperature gauge reads high, it could mean your engine is overheating. Another reason your reading might be high is you could be losing coolant. A small leak or evaporation may cause your radiator to slowly lose coolant. A third reason your temperature gauge reads high could be because the thermostat is broken. If this is the case, you may need a coolant temperature switch replacement. The last reason the temperature gauge could read high is because of a water pump, or water pump gasket failure. If the water pump is malfunctioning, it may need to be replaced by a professional.

What to Do If Your Temperature Gauge is High

If your temperature gauge is reading high, it means your car is overheating. This is a very serious matter and you should never drive an overheating car. If your car starts to overheat, shut off the air conditioner and open the windows immediately. If this does not reduce the overheating, turn on the heater as high as it can go. If this still doesn't work, pull over on the side of the road, turn off the engine, open the hood carefully, and wait until the vehicle cools down. Never open the radiator cap while the engine is hot - coolant can spray and burn you. Once the vehicle has cooled, take the car to a mechanic right away so they can diagnose the problem. Cars are especially susceptible to overheating in hot climates, like what's common in cities like Los Angeles, Phoenix, Las Vegas, or Atlanta.
The temperature gauge is an important tool in your vehicle that shows the temperature of your engine's coolant. Contact YourMechanic and have your car inspected for overheating if it reads too high, as this can cause serious problems...

Reasons the Temperature Gauge Reads Cold

On most vehicles, the temperature gauge reads cold until the engine has run for a few minutes. If the temperature gauge still reads cold after the engine has warmed up, the gauge may simply be broken. Another reason the temperature gauge could read cold is if the thermostat in the vehicle stays open. With the thermostat stuck open, the engine can be overcooled, causing a low temperature reading. If this is the case, the thermostat may need to be replaced.

i would think there is an air lock in the coolant system , have you run the engine whilst at stand still and opened the heater control to the hot position and leave to run for 10 mins or so , let cooldown then check coolant level

FLUSH RADIATOR, HEATER CORE AND ENGINE BLOCK.ADD 50 / 50 ANTIFREEZE AND WATER ALSO REPLACE RADIATOR PRESSURE CAP.IF TEMPERATURE GAUGE STILL STAY HIGH THE ENGINE COOLANT TEMPERATURE SENSOR COULD BE FAULTY.

1. With what you have replaced, the only remaining credible explanation is the Water Pump. If the Water Pump is not operating correctly, this will cause overheating. The Radiator -"side blow out"? Did the radiator cap you have on not work. Overheating should cause fluid = steam to blow out the cap and not blow out the side of the radiator.
2. One thing you can do before replacing the Water Pump is to flush your entire system. There could be a blockage in the system. These flushing kits are available at most stores (Walmart or Autoparts Stores) and you can do it yourself.
3. Was the Engine Coolant Temperature Sensor (mounted near the thermostat) also changed out? If this was malfunctioning it could be giving you a false reading.
The Water Pump is the likely culprit if the Van is truely overheating.
Let me know if this helped, or if you have additional questions or information. Feel free to contact me at FixYa.com!

your car is cooking!!!! if your heater starts to blow cold air its got an air lock in the system and need to be blead out to get this air out of the water jaket in the engine sounds like your gauge is working fine to me, its screeming at you to stop! as its over heating the engine, look under your hood for the water hoses you should find a hose with a kind of nut or screw in it at the higest point on a water hose, this is the bleed point, fill the rad up with water and turn on the heater to hot only do this when the engine is COLD undo this screw or nut start the engine up and watch the water flow out this bleed point till there is no more air coming out with the water, keep the rad full of water and you dont need to put the rad cap back on till the air has been bled out but keep the rad full of water all the time after all the air is out refill the rad or top it up put the cap back on and run the motor it should not show as hot as it was and the heater should work just fine

water pump is the problem,you will find the the water pump impellor has broken or come loose from the shaft,you going to have to replace the water pump

it sounds like the cooling system is not working properly, did you check coolant levels? then check the fans are spinning when they should be? if that is all ok check fuses for cooling system aka fan fuse, now would be a good time to mention the thremastat, if it dosnt fully open it means the colling fluid will not cycle threw the engine and it will not cool the engine properly, also note radiators that are leaking will result in low collant levels and system overheating after a short drive. fluid air and fluid moving threw engine is used to keep it all working properly, i suspect the thermastat

the temp sensor is the trigger for the fans!!
the thermostat may be in upside down??
check new thermostat in a pot of water & heat it up watch that it opens up when it heats up should be at aroun 96 degrees F
otherwise the radiator may need a good clean out or a recore!
there my be a blocked water gallery so engine may need a flush aswell
Cheers Rob