Tylerb418

2003 Honda Civic ex
Temp gauge is showing the engine is overheating but I've checked the engine with a laser thermometer and it's reading perfect. My heat inside also doesn't work unless I'm pressing the accelerator. Could this be a head gasket or just the temp gauge sensor

ezone

The gauge on the dash is operating off of the same temperature sensor the engine computer uses.

Since you say there is poor heater output, the gauge is likely telling you the truth about overheating. You can't see it with infrared temp gun because it's localized and you can't check inside the engine.

The coolant level in the radiator should be found significantly low, and there is 'air' in the cooling system causing poor heater output.
Refill the cooling system to the proper levels and the symptoms will go away----until the radiator level drops again.

Most common cause is blown head gasket.

Tylerb418

Thanks for the reply. I changed the sensor and bled the air out and it has fixed the problem. I had pressure tested the cylinders already and they were all correct. Thankfully it wasn't a head gasket.

ezone

That check can't prove the head gasket is good. You also won't find coolant and oil mixing together.


That engine will usually pass every head gasket check most people think of ---while the leakage is small.



Give it time and miles, the VERY common head gasket problems can take quite a while to resurface while the leakage is small.
It could take another 1000 miles before it has pushed enough coolant out of the radiator to cause more problems.


The forum is FULL of threads about 7th gens overheating, 98% end up being a blown head gasket.