Toyomoho, thanks for the suggestions. I had not taken the car to the dealer since the first check engine light cost $80 just to go on the machine and ended up costing over $200 for a part that had nothing to do with the drivability of the car but would have prohibited it from passing PA emissions.
The garage the car has been going to for routine repairs had contacted the Toyota factory for advise and was told that with this code, only the valve or the modulator could be the answer.
I had advised the garage that the light seemed to come on at the same point within my drive home from work and suggested that perhaps there was a connection with the fact that it often occurred right after the car had been jostled after crossing an unavoidable bump across a bridge. Perhaps that would tie in with the short in the VSV system or the disconnected vacuum or hose. I will pursue these ideas. Thanks.
Originally Posted by toyomoho
With the exception of the catalytic converter and computer, the typically federal required warranty on emissions items is 36M/36K. Your state may require longer a warranty period. Your manual or manual warranty supplement should have these details.
This code is pretty common, due a Google search on “P0401 Camry”
Other trouble areas could be:
Open or short in VSV system (this valve turns the EGR valve on/off depending on engine and driving conditions)
Disconnected vacuum or EGR hose (the EGR valve is operated by engine vacuum)
Manifold Air Pressure sensor
The modulator regulates how much the EGR valve opens based on engine load. The VSV (valve) turns the EGR system on/off based on engine (vacuum to the valve) and driving conditions and is controlled by the computer. Example: the valve is closed when the engine is at idle speed or coolant it too cold. Engine manifold vacuum operates the EGR valve.
Is this a Toyota dealer? The troubleshooting procedures for this code are very specific, plus they should have their Toyota scan tool.