GM tech MW. Labor a question.
Problem on my 2001
Pontiac Grand Prix check
engine light OBD scan code
p1404 was  pulled.  
Replaced the EGR valve, but code came back.
Any ideas much appreciated on  how to fix  this
problem. Why does my car have this issue.

If the replacement of the valve did not correct your
condition, then you need to have the
computer(pcm) re-programmed with a software
update. The update fixes a pintle position problem
that the pcm expects to see, but does not. This
must be done with a dealer scanner. Expect to pay
1 hr. Labor for this re-program.

Or the EGR passage is plugged with carbon and
needs to be cleaned. The passage runs from
under the valve, into the upper intake manifold.
Removal of the throttle body to access the passage
is needed. Use a pick or stiff wire to open up the
Basic EGR system description and operation:
The exhaust gas recirculation (EGR) system is used to lower oxides
of nitrogen  (NOx) emission levels caused by high combustion
temperature. It does this by  decreasing combustion temperature.

The main element of the system is the EGR valve. The EGR valve
feeds small  amounts of exhaust gas back into the combustion
chamber. With the fuel/air  mixture thus diluted, combustion
temperatures are reduced.

If a problem with the EGR system will not allow the PCM to control
pintle position properly, DTC P0404 should set. The PCM also tests
for EGR flow. If incorrect  flow is detected, DTC P0401 should set.
See DTC list for other EGR codes.
2001 Pontiac Grand Prix P1404 EGR Valve

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