P07D9Gear 8 Incorrect Ratio
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- A ratio code compares input or turbine speed divided by output speed with the ratio of the commanded gear; a slipping clutch or the wrong gear trips it. Ford's summaries describe the check (over 30 rpm off for more than 1.8 s, three times) for gears 1–6 only; its 10-speed bulletins show gears 7–10 as P076F, P07D9, P07F6 and P07F7. P07D9 covers 8th gear. Ford's 10R80 (F-150, Mustang, Ranger, Expedition and others) and 10R140 (2020 Super Duty) list it in bulletins on harsh or delayed shifts, caused by adaptive learning, sticking valve-body valves or a migrating sleeve in a clutch cylinder. Nissan's nine-speed Frontier and Titan set it with the MIL on; a Stellantis bulletin pairs it with P0731 on low-mileage vehicles with wrong factory adaptives. Hyundai's eight-speeds and GM's 10-speed do not use it.
- What you may notice
- Slipping or flaring engine speed in gear 8
- Harsh or delayed shifts
- Check engine or transmission warning lamp
- Gear 8 locked out, higher rpm at cruise
- Likely causes
- LikelyClutch slipping or hydraulic leak (Ford 10R: migrating sleeve in the CDF clutch cylinder)
- LikelyShift adaptives wrong or not learned
- PossibleSticking valve in the valve body
- PossibleFluid level low or fluid degraded
- RareTurbine or output speed sensor signal wrong
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €4,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.