Possible causes

– Low engine oil pressure or level
– Open or short circuit condition
– Faulty VTEC oil pressure switch
– Faulty VTEC solenoid

When is the code detected?

The P1259 is set when there is a problem in the VTEC Oil Pressure Switch circuit or VTEC Solenoid Valve circuit

Symptoms

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

P1259 ISUZU Description

The VTEC system activates the VTEC solenoid valve by command from the powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that is installed in the valve system to switch valve timing between Low and High. The PCM monitors oil pressure conditions in the hydraulic circuit of the VTEC mechanism according to the VTEC oil pressure switch downstream of the VTEC solenoid valve. If there is a disparity between oil pressure condition in the hydraulic circuit that is determined by the PCM command, and the oil pressure condition that is determined by the status of the VTEC oil pressure switch, the system is considered faulty and a DTC is stored.