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
To diagnose P07D9, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
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A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
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BlueDriver Pro Bluetooth Scanner
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Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
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LAUNCH CRP123X OBD-II Scanner
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A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
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Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
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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.