OBD-II Generic Error Code P2742: How to Fix It

Q: Can I drive my car with a P2742 code?

It depends on severity. P2742 is a medium-severity code. If your vehicle is not in limp mode and the transmission is shifting normally, you may be able to drive short distances cautiously. However, the PCM may not be accurately monitoring transmission fluid temperature, which risks transmission overheating and damage. It is strongly recommended to diagnose and repair the fault promptly rather than driving extensively with this code active.

Q: What is the difference between TFT Sensor A and TFT Sensor B?

Many modern automatic transmissions use more than one temperature sensor to monitor fluid temperature in different circuits or locations within the transmission. 'Sensor A' typically refers to the primary or first sensor in the circuit, while 'Sensor B' refers to a secondary sensor. P2742 specifically targets Sensor B, so it is important to identify the correct sensor location for your vehicle using a wiring diagram, as replacing the wrong sensor will not resolve the fault.

Q: How much does it cost to fix error code P2742?

If the fix is a simple wiring repair or connector cleaning, costs may be minimal — just your time and perhaps a few dollars in supplies. An external TFT sensor replacement part typically costs between $20 and $80. If the sensor is internal and requires transmission pan removal, labor at a shop can add $150 to $400. If a PCM or TCM update or replacement is needed, costs can rise significantly. Getting a diagnostic inspection quote from a transmission specialist is advisable.

Q: Will P2742 cause my car to fail an emissions test?

P2742 is a transmission-related fault rather than a direct emissions fault. However, because the Check Engine Light is illuminated and a fault code is stored, most states will fail your vehicle during an OBD-II emissions inspection when any active fault code is present. You will need to repair the fault and ensure all OBD-II readiness monitors have completed their drive cycles before re-testing.

Q: Can low transmission fluid cause a P2742 code?

Yes, low transmission fluid can potentially cause or contribute to P2742. When fluid is low, the sensor may not be fully submerged in fluid, causing it to read inaccurately and produce a voltage signal outside the expected range. Always check your transmission fluid level and condition as one of the first diagnostic steps. However, low fluid alone typically indicates another underlying problem such as a leak that also needs to be addressed.

Abstract

Error code P2742 indicates that your vehicle's powertrain control module (PCM) has detected an abnormally low voltage signal from Transmission Fluid Temperature (TFT) Sensor B. This sensor monitors the temperature of the automatic transmission fluid to help the PCM manage shift timing and protect the transmission from damage. When the signal falls outside the expected range, the PCM triggers this code and may illuminate the Check Engine or Transmission Warning light — and in some vehicles, it may also trigger limp mode to protect the transmission.