1999 Nissan Maxima Code P0400

Question

Replaced both EGR valve and temp sensor. Code P0400 still comes on. 99 nissan maxima.
What else can be checked?

Answer 1

P0400 NISSAN - Exhaust Gas Recirculation Function- No/Low Flow Detected

Read more: https://www.autocodes.com/p0400_nissan.html

You should clean the EGR passages. The EGR provides exhaust gases into the engine by the intake plenum, through a hole/passage where the EGR valve connects. The passage may be clogged, remove the EGR valve and clean the EGR  passage.