Temperature gauge saying hot

Hello, hopefully someone could help me. Every time I turn on my 03 2.7 tacoma the temperature gauge says it's over heating right away. I replaced the thermostat and sensor for the coolant right after the engine. But it still says even though it's not even warmed up.
Thanks in advance.

 

Does the gauge have it's own sending unit?

 

I'm not sure to be honest.

 

There are 2 sensors. One for the computer and one for the gauge.


The one for the gauges (water temp sender) is the one that is located near the water inlet into the top of the engine.
The other (engine coolant temp sensor) is for the ECU, and is located on the back of the cylinder head (pain to get at).

https://www.tacomaworld.com/threads/1st-gen-coolant-temp-sensor-help.419332/#post-11967862

 

Thank you. I did replace the front one. Havent replaced the back one. Can't figure out how to unclip the wire from the sensor and don't want to break it. Will it hurt the engine if I drive it like 20 miles?

 

Any kind of sensor either reading the min or max value at all times typically indicates a faulty sensor.

 

If you replaced the front one and your gauge is still messed up, then you’ve probably got a wiring problem.

I’d check with an obd scanner to see if the rear one is reading right. If so you’re good to drive it.

 

Ok thanks. I was going to drive it to O'Reilly and have them hook it up to see what their machine tells me. Just nervous to drive it over there I don't want to mess anything up

 

Maybe borrow a scanner to insure it isn’t actually overheating hopefully an ODB can tell you right temps

 

Did you by mistake use any thread sealer or teflon tape as that sensor grounds through the threads to the block.

Perhaps a bad sensor out of the box.

Time to test with your Meter.

 

No thread sealer. But might have to check with a meter. Didnt think of it being bad out of the box. Thank you

 

Also if you have a mechanic friend or someone with a thermal gun to check the operating temp

 

Not being electrically inclined, I would first check the obd2 temp reading to see if it matches what the dash gauge is saying, and if it's off then it's definitely something in the reading like the sensor or gauge and not a critical issue.

When you say it says it's reading high right away, you mean instantly? I would make sure the fan is running and the coolant hose gets warm in a couple minutes, the two obvious things that would make me hesitant to drive it long if those aren't ok.

 

To echo the sentiments of JustADriver and others, several years ago when my in dash temperature gauge permanently pegged in the middle of its range I installed a ScanGaugeII (after replacing the sensor in the engine and it not fixing the problem). It plugs into the OBDII port and gives me a ton of information that people driving more modern vehicles take for granted. Things like water temp, inlet air temp, RPMs (I have no tach), etc. are all just a push of a button away, plus it has the added benefit of allowing me to reset the dreaded P0136 when I get it on an annual basis! This isn't a fix to your problem but it is a backup in case your gauge is on the fritz, a problem I understand many 1st gen Tacos suffer from. Good luck.

 

Did you ever fix this having the same problem in my 2002 2.4 replaced thermostat and both sensors not fixed trying to choose obd2 scanner now to order until I can find the solution