Possible causes

– EGR volume control valve stuck open
– Faulty EGR volume control valve
– EGR solenoid valve harness is open or shorted
– EGR solenoid valve circuit poor electrical connection
– Faulty EGR temperature sensor and circuit

When is the code detected?

High Exhaust Gas Recirculation (EGR) flow control is detected

Symptoms

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

P0402 INFINITI Description

The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 and 2. If too much Exhaust Gas Recirculation (EGR) flow exists due to an EGRC-BPT valve malfunction, off idle engine roughness will increase. If the roughness is large, then the vacuum to the EGR valve is interrupted through the EGRC solenoid valve. If the engine roughness is reduced at that time, the EGRC-BPT valve malfunction is indicated.