Toyota Repair: po401, emission control device, combustion temperatures

Question
QUESTION: does po401 damage my engine what will it to my car

ANSWER: No, it will not cause damage to the engine, it is for a malfunction of the exhaust gas recirculation (EGR) system, it is and emission control device and has no affect on drivability.

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QUESTION: so what will it actually do what will be the side effects, if it does not damage the engine and its just a exaust problem what can I expect long term if not corrected. Im confused what is the purpose if egr and what will po401 do then.

Answer
Hello, the purpose of the EGR system is to recirculate some of the exhaust gases back into the intake system and into the combustion chamber, this causes lower combustion temperatures which in turn reduces nOX (oxides of nitrogen) emissions which is a known greenhouse gas, this type of system was introduced at around 1970 due to the federal clean air act legislation. The 401 code simply means that there is not enough exhaust gas being recirculated either due to a defective EGR valve, modulator valve, disconnected vacuum hoses, clogged passage between the valve and the intake system or a bad vacuum switching valve that controls the system. If you live in a location that has annual or by annual emission testing it will fail the test and the problem has to be fixed before registration renewal.