Possible causes

– Faulty Vacuum Switching Valve (VSV)
– VSV for air injection control circuit Bank 2
– Air switching valve No.2 Bank 2
– VSV for air injection system Bank 2
– Engine Control Module (ECM)

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1444 SCION Description

The Engine Control Module (ECM) detects pressure change with the pressure sensor to determine malfunctioning parts in the system,and stores the DTCs. The ECM measures pressure and/or exhaust pulsation of the system at 6 points, A to F, when the air injection system is in operation or when not in operation. When the pressure is high, the ECM determines that the pump operates. When exhaust pulsation is detected, the ECM determines that the ASV is open. The ECM determines malfunction parts based on the measured value, and stores the DTCs.

Points A and B:
ECM detects pressure changes (decrease), and determines that the ASV No.2 is open.

Points C and F:
ECM detects pressure and exhaust pulsation, and determines the pressure pattern of the system.

Point D:
ECM operate the system, as indicated by the dashed lines, to determine which of the ASV No.2 is malfunctioning only when pressure changes cannot be detected at point B.

Point E:
ECM detects exhaust pulsation to determine the condition of the system.

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