P0758: Shift Solenoid B Electrical

What does P0758 mean?

A shift solenoid is an electrically switched valve in the valve body. Manufacturers use these codes differently: Ford reports an open circuit with the base code and shorts separately, newer GM units have separate low/high codes, and the letter is not tied to a valve number (Saab's 9-5: A = valve S2). P0758 is the collective electrical code for solenoid B. GM's older 4-speeds flag open or short to ground at more than 43 of 50 failed counts; Subaru compares the driver transistor voltage for 30 ms, lights the MIL after two trips and holds third gear; on Saab's 5-speed Aisin box B is valve S3, checked by current; Hyundai's 8-speed uses it for the proportional valve of the 2-6 brake. Ford and newer GM do not use P0758.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine or transmission warning lamp
• Limp mode in a fixed gear, no upshifts
• Harsh shifts from maximum line pressure

Common causes

• High Open or corroded wire or transmission pass-through connector
• Medium Solenoid coil open or shorted
• Medium Internal harness or electronic module in the transmission
• Low Module driver faulty or valve supply missing

Likelihood is a general estimate across vehicles; your make and model may differ.