My name is ***** ***** I am a licenced diagnostic technician with over 20 years experience.
I will do my best to help you with your automotive problem. Please remember, I cannot see, hear or feel your vehicle which can make diagnosing very complicated and some vehicle require extensive diagnotics that require certain diagnostics computers that can not be done over a computer or phone.Please be patient as I am not online 24 hours a day, as I do work, but I do check my page every day.A positive rating is always appreciated for my time and knowledge to help you with your problem.
P0402 is an excessive egr flow detected.
The computer has noticed that the egr flow was a little mutch during some point of self testing.
I dont think i would be to worried about this code unless its affecting the running quality of the vehicle.
It could be the egr valve assembly or even just require a good cleaning of the egr system. excessive carbon and soot can build up and hold the valve oper causing a false code, than when you accelerate the valve opens up again and released the chunk of carbon.
I would reccomend removing the valve, inspecting it and cleaning it. clear the codes and monitor it. if it comes back on, the valve will probably have to be replaced.
Its not a big deal or anything to worry about though unless its affecting how it runs, as its mainly emmisions.
There is also a pcm flash available for this vehicle that will calm the monitor down a bit so the light is not so touchy.
I hope i have answered your question and i am always available for follow ups after ratings.
I appreciate a positive rating!