Powertrain, generic (extended)

P2743 Transmission Fluid Temperature Sensor B Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

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.

Likely causes

Open circuit – broken lead or unplugged connector at sensor B
Signal lead shorted to a voltage source
CAN fault or control unit with built-in sensor (Mitsubishi TC-SST)

Symptoms

  • 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

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–2,500
Time0.5–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

trans fluid temp sensor bwiring harness

Related codes

P2740P2741P2742P2744P0713

References: gsi.ext.gm.com, mitsubishitechinfo.com, fordservicecontent.com.