P0730 fault code: Incorrect Gear Ratio

P0730 means “Incorrect Gear Ratio” — a transmission fault in the powertrain.

Can I DIY?

Professional-only boundary. You may confirm P0730 and freeze-frame while parked; do not road-test gears or open the gearbox.

Do not DIYReviewed page boundary
ToolsSpecialist equipment

This is the conservative boundary from the reviewed code record. This page has no frozen site-wide safety grade, so it does not publish a repair route.

What to tell the garage about P0730

Do not drive. The gearbox computer commanded a gear, but the ratio it calculates from shaft speeds does not match that gear. This is a transmission ratio fault, not an engine misfire or an exhaust problem.

Take these reviewed, code-specific details with you. They help the garage confirm the fault without turning this page into a repair procedure.

  • Incorrect Gear Ratio: Registration number
  • Incorrect Gear Ratio: Exact code P0730 and every companion transmission code
  • Incorrect Gear Ratio: Freeze-frame gear or ratio if the scanner showed it
  • Incorrect Gear Ratio: Whether Park, Reverse and Drive still engage
  • Incorrect Gear Ratio: Any gearbox warning lamp, burning smell, or fluid on the ground
P07xxTransmission
MOT fail riskif the warning light stays on

What does P0730 mean?

P0730 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P07xx block, which covers transmission. The stored description is “Incorrect Gear Ratio”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0730 fail an MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off.

Before booking your test, check what usually fails on your car: see our MOT pass rates by make and model, built from 33.1 million DVSA tests.

Related guides

Car diagnostic test cost: compare the scopeUK booking marketplaces currently publish diagnostic averages of about £52–£65. Engine management light on: steady or flashing?A steady engine management light means the computer has stored a fault. Drive with caution and get the code read. A flashing light is different — stop when it is safe.
P0700Transmission Control System (MIL Request) P0701Transmission Control System Range/Performance P0702Transmission Control System Electrical P0703Brake Switch 'B' Circuit P0704Clutch Switch Input Circuit Malfunction P0705Transmission Range Sensor Circuit Malfunction (PRNDL Input) P0706Transmission Range Sensor Circuit Range/Performance P0707Transmission Range Sensor Circuit Low

P0730 — quick answers

Is it safe to drive with P0730?

Do not drive. Driveability guidance is not available for this code — treat as do not drive until checked.

Will P0730 fail my MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off.

Fault-code identifiers are standard diagnostic facts. Their explanations and diagnostic guidance on this site are original editorial summaries, not reproduced SAE wording. MOT defect rules reflect the DVSA MOT inspection manual (2026). This page is general guidance for UK drivers, not a substitute for a professional diagnosis.