1997 Toyota Camry P0401 OBD-II Code (Gas Recirculation - Insufficient Exhaust Flow)?

I have a 1997 Toyota Camry that has an ongoing exhaust system problem. First, the exhaust manifold has been running real hot for a while now - I mean red hot like it just came out of the furnace. I took the car for a smog test last month and it passed with flying colors. Temperature gauge shows normal - always just a tad above the middle. Car does not overheat or lose power, but it water hose and the radiator indicates above normal pressure. If you touch the hose after driving the car for a few minutes, you can feel the boiling water inside the hose. Engine runs smooth and quiet however. I had it check for crack head gasket and result was negative.





Two days ago the Engine Check light came on. I bought an OBD II reader and reader shows Error code P0401 (Gas Recirculation - Insufficient Exhaust Flow). I need help figuring out what's is the likely culprit so I can decide whether to fix it myself or take it to a mechanic. In case I take it to a mechanic, at least I know what the problem is so I won't get taken. Thanks for all your help.|||While the EGR system helps cool cylinder temperatures, I DOUBT that this is causing a hot manifold or high cooling system pressures... These two things should be checked by a shop... Hot manifold could be a fuel control problem of some sort, high cooling system pressure could indicate a combustion leak of the head gasket ( see if the coolant smells like exhaust fumes)





Hot manifold *could* also indicate a clogged catalytic converter, does the car run sluggish at all, or not want to accelerate well?





EGR basics: computer senses engine load, throttle position, amongst other values, and calculates desired egr flow. Egr flow is regulated by way of a pulse width modulated solenoid valve. There is a transducer in place to sense egr pipe backpressure, and help adjust egr flow accordingly... The computer then uses O2 sensor readings, knock sensor values, and other means to determine if the egr system is working properly.. Hence your P0401, computer sees a problem with egr flow.





Causes of this code are usually: clogged egr passageway(s), bad transducer (melted diaphragm), bad solenoid valve(s), broken vacuum hose(s), or bad egr valve





Are you prepared to make this diagnosis on your own? Code readers are great, and so is learning new things, but keep in mind modern engine control systems are very complex and usually requiire a pretty good understanding of theory to help make an educated diagnosis.





Have fun and good luck!|||Well.. if the exhaust is turning red hot that usually means your car is running lean..it could be caused from the timing being out of adjustment and also another problem could be the catalyst.. if the converter is clogged up it will give you an 02 sensor code and that usually means bad fuel flow or exhaust flow... I suggest you take it to a shop... it could catch fire even if it nseems the car is running good|||Camry's, especially I4's are famous for this code for some reason. On mine, I removed the egr thinking it was plugged up with carbon. It wasn't. Replaced the thing, unhooked the battery, reconnected it and the car has been fine since.





You can GOOGLE "camry egr failures" or some such thing and read all about it in some of the forums.





The hot exhaust manifold is a sign of some OTHER problem like incomplete ignition, bad converter, poor tune or something causing too much unburned fuel going into the exhaust. Better get it checked out.