As an ASE Certified Master Technician and content creator for autelfrance.com, I’m here to break down the OBD-II trouble code P0713. This code is a common issue in modern vehicles and relates to your transmission’s health. Specifically, it indicates a problem with the Transmission Fluid Temperature (TFT) Sensor A Circuit High Input. This article will provide a comprehensive guide to understanding, diagnosing, and addressing this fault, ensuring your vehicle runs smoothly.
Decoding the P0713 Trouble Code: Transmission Fluid Temperature Sensor ‘A’ Circuit High Input
The diagnostic trouble code P0713 is a generic powertrain code, meaning it can occur in any OBD-II equipped vehicle with an automatic transmission and a TFT sensor. This sensor plays a crucial role in your vehicle’s performance and longevity. The Powertrain Control Module (PCM) relies on the TFT sensor’s readings to optimize various transmission functions, including:
- Shift Points: Ensuring smooth and efficient gear changes at the right time.
- Line Pressure: Regulating the hydraulic pressure within the transmission for proper clutch and band engagement.
- Torque Converter Clutch (TCC) Control: Managing the engagement and disengagement of the torque converter clutch for fuel efficiency and performance.
The TFT sensor, often located in the transmission pan, operates on a simple principle. It receives a reference voltage, typically 5 volts, from the PCM. As the transmission fluid temperature changes, the sensor’s internal resistance fluctuates. This resistance change alters the return voltage signal sent back to the PCM.
TFT sensors are Negative Temperature Coefficient (NTC) thermistors. This means their resistance decreases as the temperature rises, and vice versa. Therefore, a higher transmission fluid temperature results in a lower voltage signal to the PCM, and a lower temperature leads to a higher voltage signal.
Code P0713 is triggered when the PCM detects an abnormally high voltage signal from the TFT sensor circuit. This “high input” condition usually indicates an open circuit in the sensor circuit, suggesting a break in the wiring or a sensor malfunction rather than excessively hot transmission fluid.
Image: A typical Transmission Fluid Temperature Sensor. Understanding its location and function is key to diagnosing P0713.
Related OBD-II Trouble Codes for the TFT Sensor “A” Circuit:
While P0713 specifically points to a “High Input,” other related codes you might encounter concerning the same circuit include:
- P0710: Transmission Fluid Temperature Sensor Circuit Malfunction
- P0711: Transmission Fluid Temperature Sensor Circuit Range/Performance
- P0712: Transmission Fluid Temperature Sensor Circuit Low Input
- P0714: Transmission Fluid Temperature Sensor Circuit Intermittent
Severity and Common Symptoms of P0713
The P0713 code ranges from moderate to severe in its impact. While it might not immediately disable your vehicle, ignoring it can lead to more significant transmission problems down the line. Addressing this code promptly is crucial for maintaining your vehicle’s reliability.
Common symptoms associated with a P0713 code can include:
- Check Engine Light Illumination: The most obvious sign, indicating a fault within the vehicle’s system.
- Improper Torque Converter Clutch (TCC) Operation: You might notice unusual vibrations or shuddering, especially at highway speeds.
- Harsh or Delayed Shifting: Gear changes may become jerky, abrupt, or hesitant.
- Vehicle Stuck in Limp Mode: In some cases, the PCM may limit engine power and transmission functionality to protect itself from potential damage. This “limp mode” restricts speed and performance.
- Reduced Fuel Economy: Inefficient transmission operation can lead to increased fuel consumption.
Potential Causes Behind the P0713 Code
Several factors can trigger the P0713 code. Pinpointing the exact cause is the goal of effective diagnosis. Common culprits include:
- Faulty Transmission Fluid Temperature Sensor: The sensor itself may have failed internally, leading to incorrect readings.
- Wiring Problems: This is a frequent cause for “high input” codes. Issues can range from:
- Open Circuit: A break in the wiring, preventing signal flow.
- Short Circuit to Voltage: The sensor circuit may be shorting to another voltage source, causing an artificially high reading.
- Corroded or Loose Connectors: Poor connections can disrupt signal integrity.
- Damaged Wiring: Physical damage to the wires due to heat, friction, or rodents.
- Transmission Problems: While less common for a “high input” code, extreme internal transmission issues might indirectly affect sensor readings.
- Faulty Powertrain Control Module (PCM): In rare cases, the PCM itself may be malfunctioning and misinterpreting sensor signals or providing incorrect reference voltage.
Diagnosing and Repairing the P0713 Fault Code: A Step-by-Step Guide
Diagnosing P0713 requires a systematic approach. Start with a visual inspection and then proceed with circuit testing. Remember to consult your vehicle’s specific repair manual for detailed procedures and wiring diagrams.
Step 1: Preliminary Visual Inspection
Begin by carefully inspecting the TFT sensor, its wiring, and connectors. Look for:
- Obvious Damage: Visually check for frayed wires, melted insulation, broken connectors, or damage to the sensor itself.
- Loose Connections: Ensure the sensor connector and any related connectors are securely fastened.
- Fluid Leaks: Check for transmission fluid leaks around the sensor area, which could indicate damage or contamination.
Repair any visible damage, clear the P0713 code using an OBD-II scanner, and test drive the vehicle to see if the code returns.
Step 2: Check for Technical Service Bulletins (TSBs)
Before proceeding further, it’s always wise to check for Technical Service Bulletins (TSBs) issued by your vehicle’s manufacturer. TSBs provide information on known issues and recommended fixes, which can save diagnostic time.
Step 3: Preliminary Circuit Testing with a Scan Tool
Utilize an OBD-II scan tool to monitor the TFT sensor data parameter. This allows you to see what the PCM is reading from the sensor in real-time.
- Disconnect the TFT Sensor: Unplug the sensor connector. Observe the scan tool reading. It should drop to a very low value, typically indicating an open circuit to the PCM. If the reading doesn’t change, suspect a wiring issue between the sensor connector and the PCM.
- Jump the Sensor Connector Terminals: Use a jumper wire to bridge the two terminals of the disconnected sensor connector. Now, check the scan tool reading again. It should jump to a very high temperature value. This confirms that the wiring to the PCM is intact and that the PCM is correctly interpreting the input. If the reading doesn’t change, there’s likely a problem in the wiring or the PCM’s input circuit.
Step 4: Sensor Resistance Testing
To test the sensor itself, you’ll need a digital multimeter (DMM) set to measure resistance (Ohms).
- Disconnect the TFT Sensor: Ensure the sensor connector is unplugged.
- Measure Resistance: Connect the DMM probes to the two sensor terminals.
- Monitor Resistance Change: Start the engine and let it warm up. Observe the resistance reading on the multimeter. As the transmission fluid temperature increases (you can monitor engine temperature gauge as a proxy for initial warm-up), the resistance value should smoothly decrease. If the resistance remains constant or doesn’t change appropriately as the engine warms up, the sensor is likely faulty and needs replacement.
Step 5: Circuit Voltage Testing
This step involves checking the reference voltage and ground circuits.
Checking the Reference Voltage Circuit:
- Ignition ON, Engine OFF: Turn the ignition key to the “ON” position, but do not start the engine.
- Measure Reference Voltage: Use your DMM set to Volts DC. Probe one of the TFT sensor connector terminals and a known good ground (like the vehicle chassis). Refer to your vehicle’s wiring diagram to identify the reference voltage terminal – it should typically be 5 volts.
- Verify Reference Voltage Presence: You should read approximately 5 volts. If no voltage is present, proceed to the next step to check for an open circuit in the reference voltage wire.
- Continuity Test of Reference Voltage Wire: Turn the Ignition OFF. Set your DMM to measure Ohms or Continuity. Disconnect the PCM connector. Identify the reference voltage pin for the TFT sensor at both the sensor connector and the PCM connector (refer to wiring diagrams). Test for continuity between these two points. An “Out of Limits” (OL) reading indicates an open circuit in the wire. A numeric reading confirms continuity. Repair any open circuit.
- PCM Reference Voltage Output Test: If the wiring is intact, re-connect the PCM connector (leave the sensor disconnected). With Ignition ON, check for 5 volts output directly at the PCM’s reference voltage pin for the TFT sensor. If there’s no 5-volt output from the PCM, the PCM itself might be faulty, although this is less common.
Checking the Ground Circuit:
- Ignition OFF: Turn the ignition off.
- Continuity Test of Ground Wire: Set your DMM to measure Ohms or Continuity. Disconnect the PCM connector. Identify the ground pin for the TFT sensor at both the sensor connector and the PCM connector (refer to wiring diagrams). Test for continuity between these two points. An “Out of Limits” (OL) reading indicates an open circuit in the ground wire. A numeric reading confirms continuity. Repair any open circuit.
- PCM Ground Verification: With the PCM connector still disconnected, check the PCM’s ground. Set your DMM to Ohms or Continuity. Probe the PCM’s ground pin for the TFT sensor and a known good chassis ground. You should have continuity (low resistance). If not, there’s a PCM grounding issue that needs to be addressed.
Step 6: Transmission Condition Assessment
If all wiring and sensor tests pass, and you’ve ruled out PCM issues, consider the possibility of internal transmission problems. This is more likely if P0713 is accompanied by other transmission-related DTCs. A thorough transmission inspection or professional diagnosis might be necessary.
Addressing Related DTC Discussions
For further insights and real-world experiences with P0713, online automotive forums can be valuable resources. Platforms like [your favorite car repair forum] offer discussions and troubleshooting tips from other technicians and vehicle owners.
Need Further Assistance with P0713?
If you’re still facing challenges with diagnosing or repairing the P0713 code, don’t hesitate to seek professional help. Consult a certified automotive technician or visit a reputable repair shop. You can also post your specific questions in online car repair forums for community support and advice.
Disclaimer: This information is for informational purposes only and should not be considered professional repair advice. Always consult with qualified technicians and refer to your vehicle’s service manual for specific diagnostic and repair procedures. We are not responsible for any outcomes resulting from actions taken based on this information. All content is copyright protected.
