Powertrain, generic · Transmission

P0789 Shift Timing Solenoid A Intermittent

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). P0789 is an intermittent fault in the circuit of solenoid A. No manufacturer document available to us uses it; manufacturers report the circuit under the base, low and high codes. A loose contact or a coil with heat-dependent dropouts is the likely cause; shift jolts and the warning lamp appear at times.

Likely causes

Loose contact at connector or harness
Coil with thermal dropouts

Symptoms

  • Shift jolts at times
  • Warning lamp comes and goes

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–700
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

P0785P0787P0788P078E

References: law.cornell.edu, saabwisonline.com.