2001 impala 3.4l

Thanks in advance. Getting a p0401 and a p0135. Have replaced the MAP sensor and the EGR valve with no improvement. Also cleaned the exhaust tube to the EGR valve and the EGR opening to the intake manifold.

Any ideas?

The P0135 is a O2 sensor code. As far as the EGR code, if you are sure there is no restriction in the EGR system, check the wiring at the terminals for the MAP and the EGR for being broken in the insulation.

Interesting cure. I thought I had cleaned the passage from the EGR valve to the intake. To be sure I removed the butterfly valve body and MAF sensor so I could see into the intake.

The opening from the EGR tunnel into the intake was clogged like you wouldn't believe. Like coal. I couldn't tell before because the passageway took a sharp turn just before the intake tunnel and I couldn't reach through from outside. Cleaned the hard tarry stuff out and problem cured.

Thanks for your help.

This is exactly what happened to my 2001 3.4... tunnel was totally blocked with hard black stickey build up... got it cleaned out and check engine light is now off and I got it inspected....