Low or degraded automatic transmission fluid (ATF), often from a slow leak or overdue service; Worn clutch packs or brake bands inside the gearbox causing slip under load; A faulty solenoid valve or valve body issue preventing correct clutch apply pressure; A failing transmission input or output speed sensor sending an inaccurate signal to the TCM; Internal hydraulic leakage from worn seals or a cracked piston, reducing apply pressure; A software or calibration issue in the TCM, or a wiring fault between the sensors and the module; Mechanical damage to the planetary gearset or one-way clutch, though this is less common than hydraulic and electronic causes

DTC codes / Jaguar codes / P1731

P1731 · JaguarInconsistent Gear Ratio

Q: What does code P1731 mean?

Inconsistent Gear Ratio. P1731 on a Jaguar means the transmission control module (TCM) has calculated a gear ratio that does not match the ratio expected for the gear it commanded, based on input shaft speed versus output shaft speed. The TCM stores this code when the discrepancy exceeds its calibrated threshold for a set period, indicating slip or an engagement problem inside the gearbox.

P1731 on a Jaguar means the transmission control module (TCM) has calculated a gear ratio that does not match the ratio expected for the gear it commanded, based on input shaft speed versus output shaft speed. The TCM stores this code when the discrepancy exceeds its calibrated threshold for a set period, indicating slip or an engagement problem inside the gearbox.

SystemPowertrain

Code typeJaguar specific

SeverityHigh

Fix difficultyProfessional

AreaTransmission

Symptoms you may notice

Illumination of the transmission malfunction light or check engine light, often with a message on the instrument cluster
Harsh or delayed shifts, or the transmission entering limp mode and sticking in a single gear
Slipping during acceleration, with engine speed rising without a corresponding increase in road speed
A thump or flare when selecting drive or reverse, or between gear changes
Often no symptoms besides the warning light if the ratio error is brief and the TCM has not yet defaulted to limp mode

Common causes, most likely first

Low or degraded automatic transmission fluid (ATF), often from a slow leak or overdue service
Worn clutch packs or brake bands inside the gearbox causing slip under load
A faulty solenoid valve or valve body issue preventing correct clutch apply pressure
A failing transmission input or output speed sensor sending an inaccurate signal to the TCM
Internal hydraulic leakage from worn seals or a cracked piston, reducing apply pressure
A software or calibration issue in the TCM, or a wiring fault between the sensors and the module
Mechanical damage to the planetary gearset or one-way clutch, though this is less common than hydraulic and electronic causes

How to diagnose and fix it

Check the transmission fluid level and condition; top up or replace fluid if it is low, dark, or burnt-smelling
Scan all modules for stored and pending codes, and read live input and output shaft speed data to confirm the ratio error
Inspect the wiring and connectors at the input and output speed sensors for corrosion, chafing, or loose pins
Test the speed sensors with a multimeter or oscilloscope for a clean, consistent signal
Perform a pressure test at the transmission test ports to check line pressure and identify hydraulic weakness
Remove the valve body for inspection and test the shift solenoids for resistance and function
If internal mechanical or hydraulic faults are confirmed, remove and overhaul or replace the transmission

What P1731 often hides in Jaguar gearboxes

A low fluid level from a leaking cooler pipe or pan gasket is one of the most common causes of an inconsistent ratio code on Jaguars, and it is frequently missed because the leak is slow and leaves no puddle.
The code does not always mean the gearbox is worn out; a dirty or failing speed sensor can report a false ratio error, so always verify sensor signals before condemning the transmission.
On some Jaguar models, a weak battery or charging system fault can cause the TCM to log ratio codes because voltage drops disturb solenoid operation, so check the charging system first.
After a fluid service or sensor replacement, the TCM may need a relearn or adaptation reset; failing to do this can leave the code returning even though the repair was correct.
A sticking valve body spool valve can cause intermittent ratio errors that only appear when the fluid is cold or hot, so road-test the car under the conditions that set the code.

Can I keep driving with P1731?

Do not continue driving normally with P1731 stored, because the transmission may slip, overheat, or fail completely and leave you stranded. If the car is in limp mode, drive only to the nearest safe location or workshop, avoiding heavy acceleration and towing.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Jaguar vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.