P0920: Gear Shift Forward Actuator Circuit/Open
What to do
Work out exactly which gears you still have. If they alternate — first, third and fifth working while second, fourth and sixth do not, or the reverse — say so plainly. That pattern points at one direction of the shift mechanism and narrows the repair immediately.
What this code means
A circuit fault in the drive that moves the shift mechanism in one direction along the gate. Some designs split the shift actuator into two separately controlled directions rather than one reversible drive, and this code covers the first of them.
The geometry set out under P0904 makes the consequence predictable, and it is the most distinctive symptom in the whole P09xx range. Moving along the gate one way engages one gear of a plane; moving the other way engages its partner. So losing a single direction does not remove a plane — it removes one gear from every plane.
The result is a car with first, third and fifth but no second, fourth or sixth, or the exact opposite. Alternating gears missing is a pattern nothing else produces, and a driver who reports it has identified the fault without any equipment at all. It is worth asking about explicitly, because most people describe it as "it keeps skipping gears" rather than noticing the alternation.
Likely causes
Start here
- Faulty gear shift actuator · specialist
- Damaged transmission wiring harness · moderate
- Corroded transmission connector · moderate
Less common
- Open circuit in actuator wiring · moderate
Rare
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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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