OBD-II code · Powertrain (generic, extended)
P2742 Transmission Fluid Temperature Sensor B Circuit Low
The second transmission fluid temperature sensor signal is below the lower diagnostic threshold. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P2742?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyInternal short in sensor element
- PossibleSignal wire shorted to ground
- Less likelyConnector pins corroded - high contact resistance
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.8–3 h
- Emissions test
- Usually unaffected
- Parts involved
- Trans Fluid Temp Sensor B, Wiring Harness
Related codes
- P274CTransmission Fluid Temperature Sensor C Circuit Low
- P275CTransmission Fluid Temperature Sensor D Circuit Low
- P273FTransmission Fluid Temperature Sensor B Over Temperature Condition
- P2740Transmission Fluid Temperature Sensor B Circuit
- P2741Transmission Fluid Temperature Sensor B Circuit Range/Performance
- P2743Transmission Fluid Temperature Sensor B Circuit High
- P2744Transmission Fluid Temperature Sensor B Circuit Intermittent
- P2745Intermediate Shaft Speed Sensor B Circuit
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.