P2740 is the umbrella circuit code for a second transmission fluid temperature sensor, labelled B. The control module supplies the thermistor with a reference voltage and flags an electrical fault when the returned signal leaves its plausible window, without separating short from open. Where B is documented, it sits outside the sump: Ford's TR9070 dual-clutch gearbox and a GM dual-clutch module of 2023/24 both use it for the fluid leaving the cooler, but report electrical faults through the split codes P2742/P2743 rather than P2740. No manufacturer publishes P2740 itself. Without a valid B value the module relies on sensor A or a default, so cooler control and hot-fluid protection get coarser; shifting usually remains normal.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
Symptoms
- Warning lamp or transmission message
- Fluid temperature B shows an implausible fixed value on the scan tool
- Cooler or hot-fluid protection works with a substitute value
Most likely causes
- Loose, corroded or damaged connector or lead to sensor B
- Sensor B thermistor open or shorted internally
- Faulty input stage in the transmission control module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
What each character of P2740 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 7: Transmission
- 40: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2740?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P2740?
The most common causes are: loose, corroded or damaged connector or lead to sensor B; sensor B thermistor open or shorted internally; faulty input stage in the transmission control module.
Related codes
- P2741Transmission Fluid Temperature Sensor B Circuit Range/Performance
- P2742Transmission Fluid Temperature Sensor B Circuit Low
- P2743Transmission Fluid Temperature Sensor B Circuit High
- P2744Transmission Fluid Temperature Sensor B Circuit Intermittent
- P0710Transmission Fluid Temperature Sensor A Circuit
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 23OBDG07
- fordservicecontent.com: OBDSM2400OUTPUT 16Jul2024 WSM final V2 MCS7001
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.