Blocked exhaust?
 

Hi, I have a '99 Camry with a p0401. I manually pushed up the diaphragm on the egr valve, and the motor stalled. From what I read, that indicates the egr ports aren't plugged. I also noticed a couple exhaust leaks, one from the manifold/header gasket, and the other in back of the engine that I haven't pinpointed yet. I checked the tailpipe, and seem to be getting some pressure back there, so I was a little stumped. Any ideas?

egr is a stepper type motor opens and shuts
see if the egr can be cleaned or replace the egr


The OBDII fault code P0401 means that the engine computer has detected that the Exhaust Gas Recirculation (EGR) system flow is insufficient. Read more how the EGR system works below.


Toyota Camry/Corolla: In Toyota Camry with the 2.2L engine, the code P0401 was often caused by a bad VSV (Vacuum Switching Valve) for the EGR, located under the intake at the back of the engine. In many cases, replacing this valve could solve the problem, however the EGR passages need to be checked for restrictions and carbon buildup and the EGR valve needs to be checked for sticking. This article describes the repair procedure.
- A faulty VSV (Vacuum Switching Valve) for the EGR can also cause the code P0401 in older Toyota Corolla.


source
OBD II code P0401 Exhaust EGR Flow Insufficient

As an update. I was trying to take the egr valve off of the exhaust line, and of course the two bolts broke off. Anyway, I put it back together without a tight seal, and the code cleared. I'm figuring a plugged cat. I tried drilling a hole in front of cat and spraying carb cleaner. Yesterday I drilled out the two bolts(tricky with the soft aluminum around the bolt). Next step, tighten it up and see if code comes back. in meantime, I ran into drive train issue. Always something.

The code can do to other issues besides a plugged EGR port. Bad VSV, EGR modulator, vacuum hose issues.

What makes you think there is problem other then the P0401 code?