Cause
Worn synchroniser
The ring that matches a gear's speed to its shaft in the instant before the sleeve slides over — the part that makes a shift silent. Worn, it lets the teeth meet while still turning at different speeds: crunch on the way into gear, resistance the shift fork must force through, and under load a gear that can walk back out of mesh.
In an automated gearbox the module feels what your hand would have felt — shifts on that rail measure slow or incomplete, and the fork position codes tell the story. A synchroniser wears together with the fork that drives it, so the pair are inspected — and budgeted — as one.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
5 of the 12 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (12)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0915 Gear Shift Position Circuit A Range/Performance Likely for this code High
- P0919 Gear Shift Position Control Error Likely for this code High
- P2849 Shift Fork A Stuck Likely for this code High
- P284A Shift Fork B Stuck Likely for this code High
- P284B Shift Fork C Stuck Likely for this code High
- P284C Shift Fork D Stuck Likely for this code High
- P284D Shift Fork A Unrequested Movement Likely for this code Stop driving High
- P284E Shift Fork B Unrequested Movement Likely for this code Stop driving High
- P284F Shift Fork C Unrequested Movement Likely for this code Stop driving High
- P2850 Shift Fork D Unrequested Movement Likely for this code Stop driving High
- P2869 Shift Fork E Stuck Likely for this code High
- P286A Shift Fork E Unrequested Movement Likely for this code Stop driving High
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.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
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.
Sign in or create an account to add what you found about Worn synchroniser.