P0789

Shift/Timing Solenoid Intermittent

Severity: High
Driving: Drive only to a garage

The shift/timing solenoid circuit is faulting intermittently. Shift quality varies between journeys and the transmission may drop into limp mode occasionally, recovering after a restart. Intermittent faults here are usually connections rather than the solenoid.

Possible causes

CommonLoose or corroded pin at the case connector
CommonFluid wicking into the connector
CommonInternal transmission harness beginning to fail
PossibleSolenoid dropping out when hot
PossibleChafed wiring

What you might notice

Shift quality varying between journeys
Occasional limp mode clearing after a restart
Symptoms only once hot
Check engine light coming and going

What to check, in order

Note whether it only happens hot, and record the freeze frame fluid temperature if the tool supports it.
Pull the case connector and inspect for fluid and corrosion.
Wiggle-test the external harness with the live data screen showing solenoid status.
Check the fluid level and condition.
Clear the code and see how long it takes to return. That tells you more about an intermittent fault than any single measurement.

Read this code from your own car

Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.

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Where this code sits

B · Body C · Chassis P · Powertrain U · Network and communication