P0729: Sixth-gear ratio evidence depends on which transmission reports the code

P0729 is commonly displayed as an incorrect sixth-gear ratio. Ford's general monitor compares the commanded ratio with speed evidence, but its TR9070 table labels the same displayed code as an unknown sixth-gear state. The reporting transmission therefore changes how the result should be interpreted.

Confirm the eligible ratio observation

For the general forward-gear example, the selector must have remained in forward range, torque and speed conditions must be met, and the transmission must no longer be shifting. Ford describes an error exceeding 30 rpm for more than 2.5 seconds, recurring six times across key cycles without detected solenoid faults.

That is not a rule for judging a single speed sample during a shift. It also is not a measured tooth-count ratio that can be applied to every gearbox carrying the generic code.

Distinguish an incorrect ratio from an unknown gear state

The TR9070 listing places P0729 in a separate state-consistency category; P074E identifies failure to engage sixth and P073B failure to disengage it. That distinction prevents an unknown-state result from being silently renamed as one particular failed shift action.

Record commanded gear, relevant shaft speeds, shift phase and companion solenoid faults. If the electrical inputs or command state are uncertain, the evidence for a mechanical ratio conclusion is incomplete. The source does not identify a clutch pack or promise that a solenoid replacement resolves this code; the matching transmission procedure remains necessary.

Source and applicability

Ford 2024–2025 gasoline OBD operation summary, July 16 2024 revision; only the cited monitor and transmission architectures. No individual vehicle fitment or universal calibration is inferred. Ford PDF, page 152. Ford PDF, page 153. Ford PDF, page 167.