Possible causes

– EGR passage clogged
– Faulty EGR Vacuum Modulator Valve
– Faulty EGR Valve
– Faulty EGR solenoid valve
– EGR solenoid valve harness is open or shorted
– EGR solenoid valve circuit poor electrical connection
– Dead (Weak) battery
– Faulty EGR temperature sensor and circuit
– Exhaust gas leaks

Tech notes

EGR flow malfunction could be caused by a clogged EGR valve or EGR tube. Before replacing any parts try cleaning the EGR valve, tube and passages. Another common part is the EGR Vacuum Modulator Valve. The EGR vacuum modulator valve controls the amount and frequency of vacuum sent to the EGR valve and often gets clogged with carbon from the engine.

When is the code detected?

– Low EGR flow control is detected

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Possible engine hesitation

P0401 2001 TOYOTA CAMRY Description

Early Exhaust Gas Recirculation (EGR) systems component s include and EGR Valve, and Engine Control