P0721 fault code: what it means

P0721: Gearbox output speed sensor reading out of range. Harsh shifts or limp mode.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

faulty output speed sensor
wiring fault
mechatronic fault

P0721 by make

BMW

Gearbox output speed sensor reading out of range. Harsh shifts or limp mode.

Usual causes: faulty output speed sensor; wiring fault; mechatronic fault

Honda

Problem in output (countershaft) speed sensor circuit. Harsh shifts or limp mode.

Usual causes: countershaft speed sensor; wiring fault

Isuzu

Output speed sensor range/performance.

Usual causes: sensor; wiring

Mercedes-Benz

Gearbox output speed sensor out of range. Harsh shifts or limp mode; 7G-Tronic speed sensors are on the conductor plate.

Usual causes: faulty speed sensor or conductor plate (722.9); oil contamination; wiring fault

Mini

Gearbox output speed sensor reading out of range. Harsh shifts or limp mode.

Usual causes: faulty output speed sensor; wiring fault; mechatronic fault

What the repair usually costs

Automatic transmission rebuild, 6-speed and up (sent to specialist)NZ$7,190–NZ$13,080 · A$6,190–A$11,830
DSG / dual-clutch mechatronic unit replacement (new or reman)NZ$4,300–NZ$7,160 · A$3,750–A$6,390
DSG mechatronic repair / rebuild (unit sent to specialist)NZ$2,070–NZ$4,800 · A$1,890–A$4,250
Electronic throttle body replaceNZ$470–NZ$1,290 · A$440–A$1,190

Not sure what P0721 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.