P0401 & P0421 Lancer 02

Question

I have replaced the EGR valve, both o2sensors, I have cleaned out my intake manifold and replaced the gasket, I have also replace the throttle body gasket. I have also replaced the valve cover gasket. I am still getting the P0401 and the P0421 and out of ideas.

Answer 1

HI there

P0421 is for the converter right off the exhaust manifold in most cases you will have to replace the converter.
For the P0401 take a look at the egr solenoid. This might be stuck on and applying the egr at all times.