1996 Toyota camry le 4 cylinders has code po401 does it damage engine what will it do. Inssuficient exaust flow

That code indicates a problem with the Exhaust Gas Recirculation Valve (EGR).
The problem might be resolved with cleaning of that part, or it may require replacement.

Yes, a clogged EGR can cause engine damage by raising the temperature in the cylinders to the point where gasoline combusts unevenly. If this is happening, you will likely hear “pinging”, which is usually described as sounding like pebbles rattling around in a tin can. If you hear that noise, ease off on the gas pedal.

It can also lead to rough running of the engine.

You need to get this fixed.

Agree with VDC except for the pinging part. The knock sensor may mask that so you won’t hear it. However, your combustion chamber temperature can get significantly higher leading to burned valves.

You need to get this fixed.

Replace you egr vsv (vacuum switching valve) on the back of the engine block. On the Camry, you should press up on the diaphragm on the egr valve to make sure it’s moves freely and also check the passages to where the egr mounts to the intake. As long as the passages are clear and the for moves freely, replacing the vsv will eliminate the p0401-insufficient egr flow. If you notice a stalling issue especially when you first get off the highway, then the valve or passages are suspect. But if all you have is the code, replace the vsv. I’m a Toyota master tech with over 15 years experience. As far as engine damage, don’t worry about ping, etc. The egr failure (if its the exhaust/gas recirculatiion valve) will NOT cause damage to the engine, just stalling. Replace the vsv. If it is stalling, rap the the valve with a hammer and the idle should smooth out. Seems to be more common on the 1996 model than the 1995 or 1997 and on. The vsv has 2 vacuum lines and an electrical connector on it and is attached by a single 12mm bolt. It’s s little tricky to replace, you need a 12mm swivel socket with a long extension. Hope this helps. It should. Over 90% success with just the vsv. There is an active test you can run with a Toyota scan tool, but…chances are you don’t have access.