P0073 fault code: Ambient Air Temperature Sensor Circuit High

P0073 means “Ambient Air Temperature Sensor Circuit High” — a fuel and air metering fault in the powertrain.

Can I DIY?

Professional-only boundary. Record a stuck-high outside-temp display; do not splice bumper wires.

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 P0073

Do not drive. The ambient air temperature circuit is sitting high, often an open wire, so the computer may assume it is much warmer outside than the real air. Some warm-up and climate logic then runs on a false hot day.

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

  • Ambient Air Temperature Sensor Circuit High: Registration number
  • Ambient Air Temperature Sensor Circuit High: Exact code P0073 and any companion codes
  • Ambient Air Temperature Sensor Circuit High: Whether the engine management light is steady or flashing
  • Ambient Air Temperature Sensor Circuit High: Whether the outside-temperature display was stuck high or blank
P00xxFuel and air metering
MOT fail riskif the warning light stays on

What does P0073 mean?

P0073 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P00xx block, which covers fuel and air metering. The stored description is “Ambient Air Temperature Sensor Circuit High”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0073 fail an MOT?

A malfunction indicator lamp that stays on fails MOT as Major. Testers do not measure ambient-sensor circuit high as a standalone item.

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.
P0001Fuel Volume Regulator Control Circuit/Open P0002Fuel Volume Regulator Control Circuit Range/Performance P0003Fuel Volume Regulator Control Circuit Low P0004Fuel Volume Regulator Control Circuit High P0005Fuel Shutoff Valve 'A' Control Circuit/Open P0006Fuel Shutoff Valve 'A' Control Circuit Low P0007Fuel Shutoff Valve 'A' Control Circuit High P0008Engine Position System Performance

P0073 — quick answers

Is it safe to drive with P0073?

Do not drive. P0073 has no verified driving guidance. Do not drive until checked. An open ambient circuit is still a stored engine-management fault when the lamp is lit.

Will P0073 fail my MOT?

A malfunction indicator lamp that stays on fails MOT as Major. Testers do not measure ambient-sensor circuit high as a standalone item.

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.