What does P0730 mean?

The measured gear ratio does not match the gear the transmission is supposed to be in.

It can be: it often indicates slipping, which can quickly damage the transmission.

Transmission

P0730 — Incorrect Gear Ratio

The ECU or TCM compares input and output shaft speeds and finds a ratio that does not match the selected gear. This points to slipping inside the transmission or a control problem.

Severity: High

Common causes

Low or burnt transmission fluid
Worn clutches or bands (slipping)
Faulty shift or pressure solenoid
Faulty input or output speed sensor
Valve body wear or internal hydraulic fault

Symptoms

Engine revs rise without matching acceleration (slipping)
Harsh or delayed shifts
Limp mode
Check engine light

How to check

Check the transmission fluid level, colour and smell
Read transmission codes and compare input/output speeds in each gear
Check the speed sensors, solenoids and wiring
Do a pressure test; a workshop may need to open the gearbox

Can you keep driving?

Not recommended: slipping quickly damages the transmission. Have it checked before further use.

Frequently asked questions

What does P0730 mean?: The measured gear ratio does not match the gear the transmission is supposed to be in.
Is P0730 serious?: It can be: it often indicates slipping, which can quickly damage the transmission.

General reference information. It does not replace a diagnosis on your own vehicle. The same code can have different causes depending on make, model year and engine; check the manufacturer's documentation or ask a technician with a scan tool.