You really need to borrow a MityVac vacuum pump/gauge from Autozone
(free with deposit) to diagnose the system. The problem may be
insufficient vacuum to open the EGR valve and not the valve itself.

So the EGR valve itself may be fine and if so you shouldn't spend
nearly $200 to replace it. I don't believe in swapping parts to fix a
problem, because it's easily turns into a good way to waste money.

If you borrow the MityVac then you can do two things and try to
isolate the problem to the valve or modulator side:

1. Connect it to the EGR valve's vacuum port. Pull vacuum with the
MityVac while the engine is idling. The engine should stall. This will
easily confirm that the valve is working.

2. Connect it to the hose that goes to the EGR valve's vacuum port and
measure the vacuum with the engine warm. Do you read increasing engine
vacuum at the hose when opening throttle past 2500 rpm?

Today I removed the EGR valve, there was some carbon, but not much.  There
was only a think layer of carbon.  I cleaned it up.  I did reset the light,
and now waiting to see if the light comes back.  If the light comes back,
does it necessarily mean that a new EGR valve will solve it?  Thanks.

How many miles are on the car?  With the engine idling, apply vacuum to the
EGR valve and see if the engine starts to idle roughly or start to die.  If
that happens, check the EGR position sensor.  If the engine does not start
to die, check the EGR tube for blockage.  Most likely, the EGR tube is
blocked with carbon buildup.  If that is the case, you can try to dig out
some of the carbon or replace the EGR valve and tube.

Hello,

My Camry '97 just failed inspection.  It is code P0401. 'Exhaust Gas
Recirculation Flow Insufficient Detected.'  Would you please give me your
recommendations.

Thanks,
Talal Itani