P0713 - Transmission Fluid Temperature (TFT) Sensor Circuit High Input

Introduction:

The P0713 diagnostic trouble code (DTC) indicates a problem with the Transmission Fluid Temperature (TFT) sensor circuit in your vehicle's automatic transmission. This code signifies that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected an abnormally high voltage reading from the TFT sensor, suggesting a potential fault within the sensor, its wiring, or the control module itself. Addressing this issue promptly is crucial to prevent potential transmission damage and ensure smooth vehicle operation.

Table: P0713 - Transmission Fluid Temperature (TFT) Sensor Circuit High Input

Topic	Description	Potential Impact
Definition	P0713: Transmission Fluid Temperature Sensor Circuit High Input. Indicates the TFT sensor circuit is reporting a voltage higher than expected to the PCM/TCM.	Incorrect temperature readings can lead to improper shift timing, reduced fuel efficiency, and potential transmission overheating.
Common Symptoms	Check Engine Light illumination. Harsh or erratic shifting. Delayed shifting. Transmission slipping. Transmission overheating. Torque converter lockup issues. Potential limp mode activation (transmission operating in a limited gear range). Reduced fuel economy.	Driving with these symptoms can exacerbate transmission problems, leading to costly repairs. Limp mode restricts vehicle performance.
Potential Causes	Faulty TFT sensor: The sensor itself may be malfunctioning and providing an inaccurate high voltage signal. Open circuit in the signal wire: A break in the wire connecting the TFT sensor to the PCM/TCM. This can be due to corrosion, damage, or a loose connection. Short to voltage in the signal wire: The signal wire is making unintended contact with a voltage source, causing the high reading. Poor ground connection: A bad ground connection for the TFT sensor can disrupt its ability to accurately measure temperature. PCM/TCM failure: In rare cases, the PCM/TCM itself may be faulty, misinterpreting the sensor signal or providing incorrect voltage to the circuit. Corroded or damaged connector: Corrosion or damage to the connector at the TFT sensor or the PCM/TCM can disrupt the electrical connection.	Misdiagnosis can lead to unnecessary parts replacement and prolonged troubleshooting. Ignoring the problem can result in severe transmission damage.
Diagnostic Procedure	1. Scan for DTCs: Use an OBD-II scanner to confirm the P0713 code and check for any related codes. 2. Inspect the TFT sensor: Visually inspect the sensor for damage and check the connector for corrosion or loose connections. 3. Check wiring: Inspect the wiring harness leading to the TFT sensor for any signs of damage, such as cuts, abrasions, or melted insulation. 4. Test sensor resistance: Use a multimeter to measure the resistance of the TFT sensor. Compare the reading to the manufacturer's specifications. 5. Check signal wire voltage: With the key on and the engine off, use a multimeter to measure the voltage on the signal wire at the TFT sensor connector. The voltage should be within the manufacturer's specified range. 6. Check ground: Verify a good ground connection for the TFT sensor. 7. Perform a wiggle test: Wiggle the wiring harness and connectors while monitoring the sensor readings with a scan tool. This can help identify intermittent wiring issues. 8. Check PCM/TCM connections: Inspect the connections at the PCM/TCM for corrosion or loose pins.	A systematic approach is crucial for accurate diagnosis and efficient repair.
Possible Solutions	Replace the TFT sensor: If the sensor is faulty based on resistance testing. Repair the wiring: Repair any open circuits or shorts to voltage in the wiring harness. Clean or replace connectors: Clean corroded connectors or replace damaged connectors. Repair or replace the ground wire: Ensure a solid ground connection for the TFT sensor. Replace the PCM/TCM: If the PCM/TCM is determined to be faulty (rare). Flush and replace transmission fluid: While not a direct solution to P0713, fresh fluid can improve overall transmission health and performance after repairs.	Proper repair ensures the problem is resolved correctly and prevents recurrence.
Tools Required	OBD-II scanner. Multimeter. Wiring diagram for the specific vehicle. Basic hand tools (sockets, wrenches, screwdrivers). Wire stripper and crimper. Connector cleaner.	Having the right tools is essential for efficient and accurate diagnosis and repair.
Related DTCs	P0711: Transmission Fluid Temperature Sensor Circuit Range/Performance. P0712: Transmission Fluid Temperature Sensor Circuit Low Input. P0714: Transmission Fluid Temperature Sensor Circuit Intermittent.	Understanding related codes can provide additional clues to the root cause of the problem.
Sensor Type & Function	Thermistor, a resistor whose resistance changes significantly with temperature. In this application, the TFT sensor measures the temperature of the transmission fluid. This information is used by the PCM/TCM to optimize shift points, control torque converter lockup, and protect the transmission from overheating. As temperature increases, resistance decreases. The PCM/TCM monitors the voltage drop across the thermistor. A high voltage reading indicates a low resistance, which, if incorrect, suggests a fault.	The TFT sensor is crucial for proper transmission operation and longevity.

Detailed Explanations:

Definition: The P0713 code specifically means the vehicle's computer (PCM or TCM) has detected a voltage signal from the Transmission Fluid Temperature (TFT) sensor that is higher than the expected range. This implies a problem within the sensor circuit, not necessarily the temperature itself.

Common Symptoms: The most noticeable symptom is the illumination of the Check Engine Light. Other symptoms can include harsh or erratic shifting, delayed shifting, transmission slipping, and transmission overheating. In some cases, the transmission may enter limp mode, which limits the available gears to protect the transmission from further damage. You might also experience reduced fuel economy and issues with torque converter lockup.

Potential Causes: A faulty TFT sensor is a common culprit, as it might be sending an inaccurate high voltage signal. An open circuit in the signal wire connecting the sensor to the PCM/TCM, caused by damage or corrosion, can also lead to a high voltage reading. Conversely, a short to voltage in the signal wire (the wire touching a source of voltage) can also cause the same issue. A poor ground connection for the TFT sensor can disrupt its ability to accurately measure temperature. In rare instances, the PCM/TCM itself may be faulty, misinterpreting the sensor signal. Finally, corroded or damaged connectors at the sensor or PCM/TCM can disrupt the electrical connection.

Diagnostic Procedure: The first step is to scan for DTCs using an OBD-II scanner to confirm the P0713 code and identify any related codes. Next, inspect the TFT sensor for physical damage and check the connector for corrosion or looseness. Inspect the wiring harness leading to the sensor for cuts, abrasions, or melted insulation. Use a multimeter to test the sensor's resistance and compare the reading to the manufacturer's specifications. With the key on and engine off, check the signal wire voltage at the sensor connector; it should be within the specified range. Verify a good ground connection for the TFT sensor. A wiggle test, where you wiggle the wiring harness and connectors while monitoring sensor readings with a scan tool, can help identify intermittent wiring issues. Finally, check the connections at the PCM/TCM for corrosion or loose pins.

Possible Solutions: If the sensor is faulty based on resistance testing, replace the TFT sensor. If there's an open circuit or short to voltage in the wiring, repair the wiring. Clean or replace corroded or damaged connectors. If the ground connection is poor, repair or replace the ground wire. In rare cases, if the PCM/TCM is determined to be faulty, replace the PCM/TCM. While not a direct fix for the P0713 code, flushing and replacing the transmission fluid after repairs can improve overall transmission health and performance.

Tools Required: An OBD-II scanner is essential for reading the diagnostic codes. A multimeter is needed to test voltage and resistance. A wiring diagram for the specific vehicle is crucial for tracing the wiring. Basic hand tools (sockets, wrenches, screwdrivers), a wire stripper and crimper, and connector cleaner are also necessary.

Related DTCs: Related codes include P0711 (Transmission Fluid Temperature Sensor Circuit Range/Performance), which indicates the sensor reading is outside the expected range; P0712 (Transmission Fluid Temperature Sensor Circuit Low Input), which indicates a voltage signal lower than expected; and P0714 (Transmission Fluid Temperature Sensor Circuit Intermittent), which indicates an intermittent signal from the sensor.

Sensor Type & Function: The TFT sensor is typically a thermistor, a resistor whose resistance changes with temperature. It measures the temperature of the transmission fluid, and this information is used by the PCM/TCM to optimize shift points, control torque converter lockup, and protect the transmission from overheating. As the fluid temperature increases, the thermistor's resistance decreases. The PCM/TCM monitors the voltage drop across the thermistor to determine the fluid temperature.

Frequently Asked Questions:

What does the P0713 code mean? It means the Transmission Fluid Temperature (TFT) sensor circuit is reporting a voltage higher than expected to the PCM/TCM. This generally indicates a problem with the sensor or its wiring.
Can I drive my car with a P0713 code? It's not recommended. Driving with a P0713 code can lead to transmission damage and decreased performance, potentially requiring more extensive repairs.
How do I fix a P0713 code? The repair involves diagnosing the cause of the high voltage reading, which could be a faulty sensor, wiring issues, or a problem with the PCM/TCM. Repairing or replacing the faulty component is the solution.
Is the TFT sensor expensive to replace? The cost varies depending on the vehicle make and model, but the sensor itself is typically not very expensive. However, labor costs for diagnosis and replacement can add to the overall cost.
Will resetting the code fix the problem? Resetting the code might temporarily clear the Check Engine Light, but it won't fix the underlying problem. The code will likely return unless the root cause is addressed.

Conclusion:

The P0713 code indicates a high voltage reading from the Transmission Fluid Temperature (TFT) sensor circuit, potentially leading to transmission problems. A thorough diagnostic process, including sensor testing and wiring inspection, is essential for accurate identification and effective repair to prevent further damage and ensure optimal transmission performance.