P2109 fault code: what it means

P2109: Throttle position sensor minimum stop out of range. PCM stops drive-by-wire (throttle held about 8 degrees open) and limits revs.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

throttle body (sensor or carbon build-up)
wiring fault
PCM

P2109 by make

Mazda

Throttle position sensor minimum stop out of range. PCM stops drive-by-wire (throttle held about 8 degrees open) and limits revs.

Usual causes: throttle body (sensor or carbon build-up); wiring fault; PCM

Subaru

Throttle position sensor A minimum stop performance.

Usual causes: throttle body (sensor/carbon); wiring fault

What the repair usually costs

Throttle body clean and idle relearnNZ$90–NZ$190 · A$100–A$200
Electronic throttle body replaceNZ$470–NZ$1,290 · A$440–A$1,190
Intake valve carbon clean (walnut blast, direct injection)NZ$530–NZ$1,190 · A$560–A$1,240

Not sure what P2109 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.