2001 pt ran fine. started running hot found leaking water pump relaced that. still ran hot,replaced radiator cap, still ran hot, replaced thermostat which was damaged. replaced that still running hot. fans do work and come on. what is left???check engine now comes on with codes 0422 and 0455. thanks for any help

 

Maybe radiator or head gasket. could also have a defective water pump blade.

 

Your P0422 code indicates that your catalytic converter is not working efficiently. This can be because it isn't, or because the computer thinks it isn't. The downstream O2 sensor (After the cat) is where the computer gets it's info to throw that code. It could be defective.

The P0455 code indicates an EVAP system malfunction. Most common is the gas cap being faulty or inserted wrong. Other suspects are the charcoal canister, vacuum lines, and the purge solenoid. It usually indicates a large leak in the system. If it plays hide and seek with you, some shops can do a "smoke" test to find a leak.

As far as the overheating goes... I'd try solving the code problems first, just in case. Then try running it (in the driveway only) without a thermostat installed. See if you have high flow through your radiator. If not, find out why. If so, look for air or oil in the fluid. Those both indicate head/head gasket leaks.

 

could be a blocked cat.?? are you losing power?and make sure your fans are working on all the speeds i think that fan have different speeds.moe