P0120 fault code: Throttle/Pedal Position Sensor/Switch 'A' Circuit

P0120 means “Throttle/Pedal Position Sensor/Switch 'A' Circuit” — a fuel and air metering fault in the powertrain.

Can I DIY?

Professional-only boundary. Confirm P0120; throttle-body or pedal-sensor work is professional on this page.

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 P0120

Do not drive. Throttle or accelerator-pedal position sensor A has a circuit fault, so the computer may not know how far you have opened the pedal or the throttle.

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

  • Throttle/Pedal Position Sensor/Switch 'A' Circuit: Registration number
  • Throttle/Pedal Position Sensor/Switch 'A' Circuit: Exact code P0120 and any P0121–P0124 or pedal-sensor codes
  • Throttle/Pedal Position Sensor/Switch 'A' Circuit: Whether the pedal felt dead, sticky, or the car surged
  • Throttle/Pedal Position Sensor/Switch 'A' Circuit: Whether limp mode or a reduced-power message appeared
P01xxFuel and air metering
MOT fail riskif the warning light stays on

What does P0120 mean?

P0120 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P01xx block, which covers fuel and air metering. The stored description is “Throttle/Pedal Position Sensor/Switch 'A' Circuit”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0120 fail an MOT?

An illuminated engine management light is a Major defect at MOT until repaired and the lamp stays off. P0120 is a throttle/pedal circuit flag; MOT also fails dangerous throttle operation on its own rules.

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.
P0100Mass or Volume Air Flow Circuit P0101Mass or Volume Air Flow Circuit Range/Performance P0102Mass or Volume Air Flow Circuit Low Input P0103Mass or Volume Air Flow Circuit High Input P0104Mass or Volume Air Flow Circuit Intermittent P0105Manifold Absolute Pressure/Barometric Pressure Circuit P0106Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance P0107Manifold Absolute Pressure/Barometric Pressure Circuit Low Input

P0120 — quick answers

Is it safe to drive with P0120?

Do not drive. We have no verified driving guidance for P0120 — treat as do not drive until checked. A throttle/pedal circuit fault can mean unexpected power or no power; it is not copied from the P0122 neighbour row.

Will P0120 fail my MOT?

An illuminated engine management light is a Major defect at MOT until repaired and the lamp stays off. P0120 is a throttle/pedal circuit flag; MOT also fails dangerous throttle operation on its own rules.

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.