Code P1259: VTEC System Malfunction Rear Bank 1

Code P1259 (VTEC System Malfunction Rear Bank 1) sets when the ECM does not see the VTEC oil pressure switch confirm a cam-profile shift after commanding the VTEC spool valve solenoid, or detects an open/shorted condition on either component's circuit. VTEC (Variable valve Timing and lift Electronic Control) uses oil pressure routed through the spool valve to lock a pin between rocker arms for the high-lift cam lobe; the pressure switch confirms that pressure actually built before the ECM trusts the engagement. Low or degraded engine oil that cannot build switching pressure, a clogged VTEC oil strainer screen starving the spool valve, a failed pressure switch, or a spool valve solenoid with a sticking or shorted coil are the common causes.