P07D9 on 2020-2023 Lincoln Aviator — Gear 8 Incorrect Ratio
1 vehicles · 1 makes
Most Reported On
P07D9 is an OBD-II diagnostic trouble code meaning “Gear 8 Incorrect Ratio.” This code sets when the transmission control module compares input speed to output speed and finds that the ratio measured in 8th gear does not match the expected value. Essentially the transmission cannot achieve or hold the correct 8th-gear ratio, indicating slippage or an engagement problem in that gear. You may feel slipping, flaring, or the transmission failing to reach or hold 8th gear. This usually points to an internal mechanical or hydraulic transmission issue. This code is most commonly reported on 2020-2023 Lincoln Aviator.
Common Causes
Diagnostic Tools
This is a powertrain code, so a basic OBD-II reader can read it. These read P07D9.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple code reader for engine (P) codes on many compatible OBD-II vehicles. It does not support every vehicle or hybrid/EV application, and it does NOT read body, chassis or network codes; confirm exact-vehicle compatibility before buying.
- Read & clear engine (P) codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth scanner with a companion app that reads beyond the engine module — ABS, SRS and transmission — plus manufacturer-specific codes on many vehicles.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X V3.0 Elite OBD-II Scanner
by LAUNCH
Handheld scanner covering the four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level tablet with all-system coverage and bi-directional control, so you can command a module rather than only read it.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
What you can do yourself, and what needs a shop
Reading the code, clearing it, and watching whether it returns is a driveway job with the right scanner. These steps are not:
- Module programming or software updates — needs the manufacturer software or a J2534 pass-through with a paid subscription.
- Replacing a control module — most are VIN-programmed and immobilizer-registered, so a new one does nothing until it is coded to your car.
- Airbag/SRS component work — a stored fault can deploy a live device.
If the vehicle is still under warranty, check for an open recall or technical service bulletin before buying anything — the repair may already be covered.
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FAQ
What does P07D9 mean?
P07D9 stands for "Gear 8 Incorrect Ratio." This code sets when the transmission control module compares input speed to output speed and finds that the ratio measured in 8th gear does not match the expected value. Essentially the transmission cannot achieve or hold the correct 8th-gear ratio, indicating slippage or an engagement problem in that gear. You may feel slipping, flaring, or the transmission failing to reach or hold 8th gear. This usually points to an internal mechanical or hydraulic transmission issue.
What are the most common causes of P07D9?
The most common causes of P07D9 are: Worn or slipping clutches/bands for 8th gear, Low or degraded transmission fluid, Stuck or faulty shift/pressure control solenoid, Valve body wear or internal hydraulic leaks, Faulty input or output speed sensor, Internal transmission mechanical wear, Failing transmission control module (less common). The specific cause varies by vehicle.
How much does it cost to fix P07D9?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P07D9?
Au7o has documented P07D9 across 1 vehicle models from 1 manufacturers: Lincoln.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.