Powertrain, generic · Transmission

P078D Shift Timing Solenoid B High

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

'Shift timing solenoid' means different parts: on GM's 4L60-E the 3-2 downshift solenoid that times the band apply on that downshift, on Aisin five-speeds (GM, Saab) the linear valve SLS that sets clutch pressure during the shift, and on the 2017–18 Genesis G80/G90 with shift-by-wire the on/off solenoids that engage drive (A) and reverse (B). Only Hyundai/Genesis is documented using solenoid B, and only with the base code P078A. No manufacturer document available to us uses this code; the description follows solenoid A (P0788: short to positive or overcurrent, on GM's Aisin-type unit above 1356 mA for 2 s). Warning lamp and limp mode follow; the opposite is P078C.

Likely causes

Short to positive

Winding short

Symptoms

Warning lamp
Limp mode

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€100–800

Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

shift timing solenoidtransmission wiringtransmission control module

Related codes

P078A P078C P0788

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.