Transmission Fluid Temperature Sensor Circuit High
The P2743 code indicates that the transmission control module (TCM) has detected a voltage signal from the transmission fluid temperature (TFT) sensor that is higher than the expected range, typically above 4.9 volts. This sensor is a thermistor that changes resistance with temperature; a high voltage reading suggests an open circuit, high resistance, or a short to voltage in the sensor or its wiring. This can lead to incorrect temperature readings, causing the TCM to default to a safe mode, potentially affecting shift quality and transmission protection.
1. Most Common Causes
- Open circuit in the TFT 'B' sensor signal wire
- Short to battery voltage in the signal wire
- Damaged, corroded, or disconnected sensor connector
- Faulty transmission fluid temperature sensor 'B'
- Internal TCM/PCM failure (uncommon)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifts
- Transmission stuck in limp mode or failsafe
- Poor fuel economy
- Transmission overheating or improper cooling
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the TFT sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Using a multimeter, measure the resistance of the TFT sensor at different temperatures (compare to manufacturer specs).
Step 4: Check for voltage at the sensor connector (should be around 5V reference). If voltage is high, check for shorts to power.
Step 5: If sensor and wiring are okay, test the TCM by checking signal voltage at the TCM connector.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the transmission may enter limp mode, causing poor performance and potential internal damage. Short trips to a repair shop are acceptable if the transmission is not overheating.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement, but can be higher if wiring repairs or TCM replacement is needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.