My evo 7 temperature gauge going up to hot as the ignition turn on. Has been replaced the temp sensor and still the same. Same as the fuel gauge sometimes playing up.

 

Are you sure you replaced the sensor for the gauge as there are 2 sensors 1 which send info to the ecu and the other goes to the gauge on the cluster.

 

There is also the radiator thermostat. I'm not sure if you meant while the engine is running. If it's not then forget what I said.

 

If your car isn't ACTUALLY overheating I'd look into getting the thermostat checked out. Most likely that

 

I would try disconnecting the temp sensor plug to see if the issue still persist. That would rule out a bad sensor or the culprit is in the wiring. Good luck

 

check the continuity on the wires all the way back to the ECU.
might have a broke wire somewhere in the harness.

 

or actually... on the "wire"...
i think there only one on the temp sensor that controls the gauge on the dash.

 

had this issue back in 2007. traced to a leak on the gauge sensor on the t-stat housing and a marginal wire. replaced sensor, fixed leak and replaced the terminal end ( soldered a new terminal on). Covered with a vinyl boot. No issues since

 

It Wasn't overheat. I check the wiring and seems to be alright, ang check the other small sensor on the thermo stat housing saw a little bit rust,

 

The sensor for the gauge has crapped out. Mine did the same thing. The timing sucked bc I had just done a service on the cooling system so I thought my thermostat was shot or I had an air pocket or something along those lines. It wasnt until I plugged in my laptop and realized that evoscan was showing normal coolant temps so that is when it dawned on me that my issue was simply the sensor.

Im about 99% sure that is your issue. Simple and cheap fix. Good luck!

 

If all that fails check your grounding cables.

 

oh yea... this^^^

your ground to the intake manifold , if left off, will mess with your temp gauge reading.

 

Check grounds.
Disconnect sensor and turn key on. What does guage read?
Substitute cluster with good known.

 

I Just had this issue with an evo 8 I just picked up. the ground from body to intake manifold was missing.. added it problem solved. temp was going up and down like crazy even all the way to the top.

 

Replaced the sensor, and has nothing changed temp gauge still go up. Try to unplug the connector and the gauge slowly going down. Same when plug in it will going up.