P0730
Incorrect Gear Ratio
- Severity
- High
- Driving
- Drive only to a garage
The transmission is not achieving the gear ratio the module expects, without the module naming which gear. The ratio it measures between input and output shaft does not match any gear it believes it has selected. As with the per-gear codes, this usually reflects a real mechanical or hydraulic problem rather than a sensor fault.
Possible causes
- CommonLow or badly degraded transmission fluid
- CommonWorn clutches or bands
- CommonFailed shift solenoid or sticking valve body
- CommonLow line pressure - worn pump, blocked filter or failed pressure control solenoid
- PossibleFaulty speed sensor
- PossibleNon-standard tyre or differential ratio confusing the calculation
What you might notice
- Slipping or flaring between gears
- Transmission stuck in limp mode
- Harsh or unpredictable shifts
- Poor acceleration for the engine speed
- Burnt smell from the fluid
What to check, in order
- Check the fluid level and condition first.
- Read all stored codes together. This code rarely appears alone, and the codes beside it usually identify which gear and which component.
- Compare input and output shaft speed on the live data screen in each gear you can reach.
- Check the fluid filter if the transmission has been in service a long time without one. A blocked filter starves the pump and produces low pressure everywhere.
- Ask whether tyres, wheels or a differential have been changed to non-standard sizes.
- Get a professional assessment before spending. Distinguishing a solenoid from a worn clutch pack usually needs a pressure test.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Transmission
P0700P0701P0702P0703P0704P0705P0706P0707P0708P0709P0710P0711P0712P0713P0714P0715P0716P0717P0718P0719P0720P0721P0722P0723P0724P0725P0726P0727P0728P0729P0730P0731P0732P0733P0734P0735P0736P0737P0738P0739P0740P0741P0742P0743P0744P0745P0746P0747P0748P0749P0750P0751P0752P0753P0754P0755P0756P0757P0758P0759P0760P0761P0762P0763P0764P0765P0766P0767P0768P0769P0770P0771P0772P0773P0774P0775P0776P0777P0778P0779P0780P0781P0782P0783P0784P0785P0786P0787P0788P0789P0790P0791P0792P0793P0794P0795P0796P0797P0798P0799