P2743Transmission Fluid Temperature Sensor B Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2743 is the counterpart of P2742: the sensor B signal is above its valid range. In GM's 2023/24 dual-clutch TCM the cooler temperature sensor must exceed 4745 mV for 500 ms, Type B; with an NTC thermistor fed from 5 V that points to a broken wire, an unplugged connector or a short to supply voltage, and the reading looks extremely cold. Ford uses P2743 as the out-of-window-high check of the TR9070 cooler-out sensor. Mitsubishi's 2009 Lancer Twin Clutch SST again reasons in temperature: 150 °C or more for 400 ms sets the code, and it advises checking the CAN bus first because bus faults can produce a false entry. Without B the module can no longer judge the cooler outflow and falls back on sensor A.
- What you may notice
- Warning lamp or transmission message
- Scan tool shows sensor B extremely cold (GM, Ford) or extremely hot (Mitsubishi)
- Cooler control falls back on sensor A
- Likely causes
- LikelyOpen circuit – broken lead or unplugged connector at sensor B
- PossibleSignal lead shorted to a voltage source
- RareCAN fault or control unit with built-in sensor (Mitsubishi TC-SST)
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.