P0165 fault code: O2 Sensor Circuit Slow OBDResponse

P0165 means “O2 Sensor Circuit Slow OBDResponse” — a fuel and air metering fault in the powertrain.

Can I DIY?

Professional-only boundary. Record P0165; slow third-probe response on bank 2 is not a DIY emissions ladder.

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 P0165

Do not drive. Bank 2 sensor 3 is switching too slowly. Lag on that rarely fitted third probe is a response-time flag for bank 2, not a copy of a bank-1 heater page and not an old-site emissions ladder.

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

  • O2 Sensor Circuit Slow OBDResponse: Registration number
  • O2 Sensor Circuit Slow OBDResponse: Exact code P0165 and any companion codes
  • O2 Sensor Circuit Slow OBDResponse: Whether the engine management light is steady or flashing
  • O2 Sensor Circuit Slow OBDResponse: Print or photo of the scan showing sensor-3 lag, if the garage already captured it
P01xxFuel and air metering
MOT fail riskif the warning light stays on

What does P0165 mean?

P0165 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 “O2 Sensor Circuit Slow OBDResponse”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0165 fail an MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off.

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

P0165 — quick answers

Is it safe to drive with P0165?

Do not drive. We have no verified driving guidance for slow bank-2 sensor-3 oxygen response. Escalate to stop-until-checked. Do not follow a catalytic-converter or EGR remove-and-clean ladder for this code.

Will P0165 fail my MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off.

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.