P0401 "egr insufficient flow" can indicate many things, including:
1-vacuum line plugged or leaking 2-pipe from exhaust to egr valve plugged 3-pipe to vacuum modulator valve from egr valve plugged 4-passages at egr are plugged 5-bad egr valve 6-bad EGR VACUUM MODULATOR VALVE
I tried cleaning egr modulator valve, (beside/above egr)removed and tested egr vacuum & movement, inspected and cleaned all vacuum lines openings and pipes. All above did not work. I replaced the egr vacuum modulator valve. Light went out without a reset in about 30 miles of driving. Not sure if this valve can be cleaned. Retails for $69.US
clean out or replace the throttle body spacer...
Replace the Mazda engine.
No, you do not have to remove the engine to replace a radiator hose.No, you do not have to remove the engine to replace a radiator hose.
The Diesel engine
The whole thing my guy
Replace the engine.Replace the engine.
you can but you have to replace gas lines and tank and some sensors
Check for insufficient fuel delivery.
Exhaust gas recirculation insufficient flow detected
Trouble code P0401 means:Exhaust gas recirculation flow insufficient detected
Can you replace your 2000 Camry CE 4-cylinder engine with a 1997 Camry engine?"
yep, though you may have to replace the mounts.