Catalytic converter



I have a 2001 infiniti I30 that overheats when I drive at highway speeds for an extended amount of time (1hour or so). Would a clogged catalytic converter cause this to happen?


It might, but that would also come with other symptoms such as poor acceleration and a CEL light.

More likely you have a cooling system problem. A bad T-stat not fully opening, a clogged radiator, a water pump with eroded impellar vanes, maybe even a bad radiator cap (water not pressurized will boil out at lower temps), unlikely to be a bad fan since it happens on the highway. When was the last time you checked your cooling fluid level?

Check your coolant level and post back.


No, a clogged catalytic converter would likely prevent you from sustaining highway speeds. In addition, your check engine light would vigorously complain to you. I recommend you check your overheating problem by investigating the car’s cooling system.


Agree, an obvious cause for overheating is the cooling system not doing its job, unless you are towing a very heavy load. A bad catalytic converter would show up in reduced power or burning floor mats if it was overheating. Inspect and service the cooling system as needed; a sticking thermostat and all the other symptoms mentioned above could apply. Some cars in the past, such as the infamous Chevy Vega, and early Jaguars, had cooling systems that were designed too small, and overheated right out of the showroom in California and Texas. I don’t expect an Infiniti to have an underdesigned cooling system, but at 6 years of age, a clogged cooling system is very possible.


A really dumb question, but do you have enough coolant in the system. I actually have a relative who had his car overheat, asked me what caused it, and a coolant level check showed half of it was gone!


A clogged converter, if you have one, should show a loss of performance and fuel mileage.
If the coolant level is fine, the fans are operational, and the radiator is not clogged, a possibility could be a missing airdam if the vehicle is equipped with one; or was equipped with one.

Many cars use them and they are a small plastic strip mounted underneath the lower radiator support. Their job is to force additional air upwards through the radiator when the car is at speed. A missing airdam will cause a car to run hot on the highway but will not affect it at idle or low speed.
Many airdams go missing without the owners knowledge due to curbs and critters on the highway breaking them off.

Just a thought anyway.


i have had a radiator flush, replaced the T-stat 2x, replaced the water pump. There are no leaks and the fan runs constantly as soon as the car reaches operating temp. It doesn’t seem to overheat in city driving.