P2740 fault code: Transmission Fluid Temperature Sensor 'B' Circuit

P2740 means “Transmission Fluid Temperature Sensor 'B' Circuit” — an extended powertrain range fault in the powertrain. We do not yet publish verified symptoms, causes or repair steps for this code — treat an engine management light seriously and book a garage if you are unsure.

Can I DIY?

Not from this page. P2740 has no verified safety grade here yet, so we publish no DIY checks, repair steps or tool guidance for it. Treat an engine management light seriously and have the fault confirmed by a qualified garage.

Stop when it is safe to do so and arrange recovery if the engine management light is flashing, the car judders, overheats or loses power, or you can smell fuel or exhaust fumes inside the car.

P27xxExtended powertrain range
MOT fail riskif the warning light stays on

What does P2740 mean?

P2740 is a powertrain code from the extended SAE range reported by your car’s engine control unit. It sits in the P27xx block, which covers extended powertrain range. The stored description is “Transmission Fluid Temperature Sensor 'B' Circuit”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P2740 fail an MOT?

An illuminated engine management light is a Major defect at MOT since 2018 — an automatic fail until the fault is repaired and the light stays off. Clearing the code without fixing the cause is not a repair.

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.
P2700Transmission Friction Element 'A' Apply Time Range/Performance P2701Transmission Friction Element 'B' Apply Time Range/Performance P2702Transmission Friction Element 'C' Apply Time Range/Performance P2703Transmission Friction Element 'D' Apply Time Range/Performance P2704Transmission Friction Element 'E' Apply Time Range/Performance P2705Transmission Friction Element 'F' Apply Time Range/Performance P2706Shift Solenoid 'F' P2707Shift Solenoid 'F' Performance or Stuck Off

P2740 — quick answers

Will P2740 fail my MOT?

An illuminated engine management light is a Major defect at MOT since 2018 — an automatic fail until the fault is repaired and the light stays off. Clearing the code without fixing the cause is not a repair.

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.