Transmission Fluid Temperature Sensor Circuit Low
The P2742 code indicates that the transmission control module (TCM) has detected a low voltage signal from the transmission fluid temperature (TFT) sensor circuit. This sensor is a thermistor that changes resistance with temperature; a low voltage reading typically means the sensor is reading an extremely high temperature or there is a short to ground in the circuit. This can cause the TCM to default to a safe mode, potentially affecting shift quality and transmission protection.
01. Most Common Causes
- Faulty transmission fluid temperature sensor
- Short to ground in the TFT sensor circuit
- Damaged wiring or connector
- Corroded or loose electrical connections
- Faulty transmission control module (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifting
- Transmission stuck in limp mode
- Poor fuel economy
- Transmission overheating
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional transmission-related codes.
Step 2: Visually inspect the TFT sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Measure the resistance of the TFT sensor at different temperatures and compare to manufacturer specifications.
Step 4: Check for a short to ground by disconnecting the sensor and measuring resistance between the signal wire and ground.
Step 5: If the sensor and wiring are okay, test the TCM for proper operation or update software.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can cause transmission overheating and damage. Limp mode may limit speed and shifting.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and replacement of the sensor, but can be higher if wiring repairs or TCM replacement is needed.