P0099 fault code: Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic

P0099 means “Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic” — a fuel and air metering fault in the powertrain.

Can I DIY?

Professional-only boundary. Log P0099 and the conditions; wiggling live IAT-2 wiring is not a published check here.

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 P0099

Do not drive. Intake air temperature sensor 2 is flickering, so the computer cannot rely on a steady second air-temp signal from one moment to the next.

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

  • Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic: Registration number
  • Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic: Exact code P0099 and how often it returns after a clear
  • Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic: Road conditions when it set (wet, hot, bumpy)
  • Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic: Whether the light is steady, flashing, or only comes on sometimes
P00xxFuel and air metering
MOT fail riskif the warning light stays on

What does P0099 mean?

P0099 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 “Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0099 fail an MOT?

An illuminated engine management light is a Major defect at MOT until the fault is repaired and the lamp stays off. P0099 is intermittent by name; a lamp that is on in the MOT bay still fails.

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.
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P0099 — quick answers

Is it safe to drive with P0099?

Do not drive. We have no verified driving guidance for P0099 — treat as do not drive until checked. An erratic circuit can vanish on a re-scan and still be unsafe to chase in a running engine bay.

Will P0099 fail my MOT?

An illuminated engine management light is a Major defect at MOT until the fault is repaired and the lamp stays off. P0099 is intermittent by name; a lamp that is on in the MOT bay still fails.

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.