P0789: Shift Timing Solenoid A Intermittent
What to do
Mention if shift quality varies between journeys or gets worse the longer you drive. A short test drive from cold may well not reproduce this.
What this code means
The shift timing solenoid circuit is behaving inconsistently, so shift quality varies with no pattern the driver can identify — good one journey, poor the next. Internal harness faults aggravated by heat are the usual cause, and the fault will normally be provoked more reliably by a long warm run than by a cold test drive.
Likely causes
Start here
- Damaged transmission wiring harness · moderate
- Fluid tracking into the transmission connector · moderate
- Failed shift timing solenoid · moderate
Less common
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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