Exhaust gas recirculation flow malfunction and how to repair?

emission inspection report|||Agree with Michael,





It sounds like you are refering to a description of an OBDII code like P0400.


Note that P0401 is for low EGR flow,, P0402 is for excessive EGR flow.





Note that this does NOT say your EGR valve is bad. It says that the O2 sensor is sensing that when the circuit to the EGR valve is energized that the O2 values in the exhaust stream do not fluctuate like the computer senses they should. It is likely the EGR valve but you need to make sure it is that (or not something else) before simply replacing it.





Where any of the GAS readings high on either your 15 or 25mph emissions test..if so which.





Next time provide full details as it makes it easier to understand the vehicle


Make, Model, Year, Engine size, Milage,


Any other symptoms? (Your Check Engine light is probably on or the bulb has burned out)


Any service work done recently?|||The EGR valve has to be removed and tested and if good cleaned up. If bad, you need a new one.


Also the passageways that the EGR valve empties into the manifold have to be cleaned out, sometimes requiring using a small chisel on the carbon buildup.


The system gives less pollution by taking a part of your exhaust and putting it back into the combustion chamber.