Hi guys, my wife's 2001 Civic auto LX with 156k is overheating and struggles to make power over 5k RPM. The previous owner said he replaced the radiator. When I drive over 65 it starts to overheat, when I let it idle it starts to over heat after sitting for about 5 minutes. Mind you this is all in 100+ degree dry heat. It needed a new CAT to pass smog and I was hoping the old one was clogged and the new one would solve my problems. But alas it only solved the CEL. What is going on.

 

Check to see if the Tstat has been replaced yet. It may not be opening fully.

 

Update: I replaced the multiplex control unit under the dash which fixed my dash brake light that was stuck on, central locks that weren't working, the a/c now works and the car doesn't overheat at idle anymore however it does still overheat on the freeway on occasion but cools off at slower speeds. The car also smells like gas when I turn it off and I got a code p0128 and a pending p1457. I'm going to try a new thermostat and check the charcoal canister vent valve.