Circuit Description

WARNING: This page is about a different car, the 1995 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

See CODE P0401 - INSUFFICIENT EXHAUST GAS RECIRCULATION FLOW DETECTED . Code is set when Exhaust Gas Recirculation (EGR) gas temperature sensor value is high. Engine not yet at normal operating temperature. Possible causes are:

EGR valve stuck open.
EGR Vacuum Switching Valve (VSV).
EGR VSV open circuit.
EGR gas temperature sensor short circuit.
ECM.