P0789

Shift Timing Solenoid A Intermittent

Transmission (shift-timing solenoid) Generic OBD-II Medium

What it means

P0789 means the transmission control module has detected an intermittent electrical fault in the shift-timing solenoid A circuit, which fine-tunes when gear changes occur. Because it comes and goes, shift quality can be normal much of the time and then briefly rough or delayed. Intermittent faults usually trace to wiring and connectors rather than the solenoid.

Medium

Can I keep driving? Drivable, but shifts may occasionally be rough, delayed, or slip; repair it before the intermittent fault becomes permanent.

Common symptoms

What you'll notice

Occasional rough, delayed, or harsh shifts
Shifts that slip or flare intermittently
Transmission may briefly enter limp mode
Check-engine light on

Common causes

Most likely first

Loose, corroded, or chafed wiring/connector at the solenoid (typical of intermittent faults)Likely
Failing shift-timing solenoid ACommon
Contaminated transmission fluid affecting the solenoidCommon
Faulty transmission control module (rare)Less often

How to diagnose & fix

Work through it in order

Wiggle-test the solenoid harness and connector while monitoring the code.
Repair corroded or loose connections in the solenoid circuit.
Check transmission fluid level and condition; service if dirty.
Measure solenoid resistance and replace the shift-timing solenoid if out of spec.
If wiring and solenoid are good, evaluate the TCM.

FAQ

Quick answers

Is it safe to drive with P0789?+

Short-term yes, since the fault is intermittent, but occasional slipping shifts can wear the clutches over time, so don't ignore it.

Can I just clear P0789?+

It will set again the next time the solenoid signal drops out; intermittent codes need the wiring or solenoid fault found and fixed.

Related codes

Often seen with P0789

P0785Shift Timing Solenoid A P0787Shift Timing Solenoid A Low P0788Shift Timing Solenoid A High P078EShift Timing Solenoid B Intermittent

Read & clear P0789 yourself

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✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX