SES Light - P0404, P1400, P1404 errors

[smoranos]

My SES light on my 99 Tahoe came on about 400 miles ago (while on vacation of course) and after stopping by an Auto Zone, I have 3 error messages, P0404, P1400, P1404. They are telling me I need an EGR valve. The car is starting to idle rough and I was wondering if others feel the EGR will fix the problem or am I in for bigger problems that an ASE mechanic will need to handle?

Thanks in advance for your time.

[Jeremy-WI]

Try removing the egr and cleaning it up with some throttle body cleaner and check the engine ports for carbon build up

[GMMerlin]

With the P0404 (Egr Open performance) and a P1404 (Egr closed performance) codes, I would remove the EGR valve and inspect.
Most likely with those codes and a rough idle condition, the valve is stuck open..most likely from a mechanical failure of the valve (carbon deposits are not common in that engine)
You can replace the valve yourself.