P0051 Auto Trouble Code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.
When you turn on the ignition, the Service Engine Soon or Check Engine P0051 light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. You'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the car!
The problem is caused by the variable cylinder management system switching on and off during light throttle conditions, at cruising speeds, or when driving on flat roads. The constant switching causes excessive oil consumption and the trouble codes appear when oil pressure drops to the point where it can no longer operate the VCM system.
Power Steering Pressure (PSP) Switch Signal Malfunction The PCM counts the number of times vehicle speed transitions from 0 to a calibratable speed. After a calibratable number of speed transitions the PCM expects that the PSP input should have changed. This DTC is set if the transition is not detected. Vehicle towed with engine running Power steering hydraulic concern was repaired but DTC was not erased PSP switch/shorting bar damaged SIG RTN circuit open PSP circuit open or shorted to SIGRTN PCM damaged Check, if possible, if vehicle was towed or power steering service was performed. Observe PSP V PID while checking wires for intermittents.