Fix P0713: Mechanic’s solutions that WORKED

The code P0713: “Transmission Fluid Temperature Sensor A Circuit High Input” points to a fault in the transmission fluid temperature sensor circuit, indicating that the sensor is reading a high input signal.

P0713 quick overview

Meaning	P0713: “Transmission Fluid Temperature Sensor A Circuit High Input”
Is it serious?	Yes, it can affect transmission shifting and performance.
Possible causes	– Faulty transmission fluid temperature sensor. – Damaged or corroded wiring in the sensor circuit. – Poor electrical connections. – Issues with the transmission control module (TCM).
How to diagnose?	Check sensor wiring: Inspect the wiring harness for damage or wear, especially if it was reused during transmission work. Inspect connections: Carefully examine and tighten electrical connections, including those on the transmission and TCM, to ensure good contact. Test sensor: Isolate the sensor wires and apply a load to evaluate their functionality. Consider sensor replacement: If wiring and connections are fine, consider replacing the transmission fluid temperature sensor, especially if it’s attached to the filter.

The P0713 code indicates a problem with the transmission fluid temperature sensor circuit. This sensor is responsible for monitoring the temperature of the transmission fluid. When it detects a high input signal, it means that the sensor is reading a temperature that is outside the expected range. This issue can affect the proper functioning of the transmission and lead to harsh shifting. Common causes include a faulty sensor, damaged wiring, poor connections, or problems with the transmission control module. It’s essential to diagnose and address this issue to ensure the transmission operates correctly.

How to fix P0713 – learn from mechanics

I looked into P0713 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Hyundai

Vehicle Information:

• Make, Model, Year: 1999 Hyundai Elantra GL 2.0L

Issue + Repair History:

• Customer reported MIL (Malfunction Indicator Lamp) on when fuel level is below half tank.
• Codes found: P0713 (Trans Fluid Temp Sensor A Circuit High Input) and P1624 (Manufacturer Specific).
• No repair history mentioned.

Other OBD2 Codes + Test Results:

• P0713 and P1624 codes mentioned.

Suggestions to Fix Issue:

• Diagnose P0713 code for trans fluid temp fault and address it.

Final Fix:

• Fixing the temp sensor code (P0713) resolved both codes (P0713 and P1624).

Case #2: Pontiac

Vehicle Information:

• Make, Model, Year: 1995 Pontiac Sunfire SE 2.3L

Issue + Repair History:

• Check engine light on.
• Scanned for codes and found P0713 (Trans Temp Sensor Circuit High).
• No repair history mentioned.

Other OBD2 Codes + Test Results:

• No other codes or test results mentioned.

Suggestions to Fix Issue:

• Check wiring for problems, which yielded no issues.
• Checked the sensor itself and found it to be defective.

Final Fix:

• The issue was resolved by replacing the defective trans temp sensor (P0713).

Case #3: Mazda

Vehicle Information:

• Make, Model, Year: 1996 Mazda B4000 LE 4.0L

Issue + Repair History:

• Check engine light on.
• Scanned codes for transmission: P713 (Trans Range Sensor) and P708 (Trans Fluid Temp).
• No repair history mentioned.

Other OBD2 Codes + Test Results:

• No other codes mentioned.
• Voltage when looking at the computer for the trans range sensor reads 5 volts in all gears.

Suggestions to Fix Issue:

• Confirm the ground circuit.
• Check the ground circuit for the sensors (common ground).
• Add a ground strap from the frame to the engine.
• Check ground connections.

Final Fix:

• The issue was resolved by repairing the ground wire from the battery to the frame and ensuring proper grounding.

Case #4: Ford

Vehicle Information:

• Make, Model, Year: 1997 Ford F Super Duty 7.3L

Issue + Repair History:

• Late upshift after a 25-mile drive.
• Engine needs to rev to 3,000 RPM before the shift occurs.
• Temperature did not get above 100 degrees.
• New customer, no repair history mentioned.

Other OBD2 Codes + Test Results:

• P0713 and P0344 codes were found.
• Lab scope testing determined that the cam position frequency was low and erratic, affecting the RPM signal to the PCM and causing late shifting.
• Replaced the camshaft position sensor, and the vehicle now shifts correctly at the right speeds.

Suggestions to Fix Issue:

• Check if the computer is commanding the shift.
• Cold engine temperature can cause late shifts.
• Check the TFT (Transmission Fluid Temperature) sensor.
• Reflash the Super Duty’s computer.
• Check the FIP (Fuel Injection Pressure) sensor for problems.
• Inspect the VSS (Vehicle Speed Sensor).
• Check the FIPL (Fuel Injection Pump Lever) for issues.
• Ensure proper grounding.

Final Fix:

• Replaced the camshaft position sensor to address the low and erratic cam position frequency, which was affecting the RPM signal and causing late shifting.
• Replaced the engine thermostat to bring up the engine temperature, which did not affect transmission shifting but had an impact on the mph at which the TCC (Torque Converter Clutch) applied.

Case #5: Mazda

Vehicle Information:

• Make, Model, Year: 2008 Mazda 3 S 2.3L

Issue + Repair History:

• Intermittently sets a P0713 transmission temperature sensor code.
• Harsh shifts occur when the code sets.
• Typically happens after the vehicle has been driven for 20 minutes or more.
• Client claims the transmission and TCM (Transmission Control Module) have been replaced three times.
• When monitoring the transmission temperature with a scan tool, it reads normal until it suddenly drops to either -40°F or -22°F, at which point the code sets.
• Checked continuity of the wire from the transmission to the TCM terminal AA, which appeared to be okay at 0.2 ohms.

Other OBD2 Codes + Test Results:

• P0713 code identified.
• Continuity test of the wire between the TCM and transmission temperature sensor was conducted and found to be satisfactory at 0.2 ohms.
• Trouble tree in Alldata indicated that there should be 4.6 volts or less at terminal AA of the TCM when the key is turned on. However, during the issue occurrence, only 0.235 volts were observed.

Suggestions to Fix Issue:

• The TFT (Transmission Fluid Temperature) circuit is NTC (Negative Temperature Coefficient) based.
• The TCM outputs the signal to the NTC sensor and receives it back.
• -40°F reading typically indicates that the voltage has exceeded the upper limits of the normal operating range.
• Possible causes include an internal TCM fault, a short to power on the signal line, or an open circuit.
• Check for a faulty CTS (Coolant Temperature Sensor).
• Inspect the wiring harness for damage, especially if it was reused during a transmission rebuild.
• Consider replacing the temp sensor, which is attached to the filter, if the harness and connections check out.

Final Fix:

• The issue was resolved by addressing two bad connections:
  1. Connector on the transmission’s green/white wire was taken apart and tightened on the female side.
  2. The AA pin connector at the TCM was disassembled and tightened.
• This fixed the original problem of the P0713 code related to the transmission temperature sensor.
• However, a new issue arose with a P0753 shift solenoid A code, which was traced back to a faulty TCM.
• The client was waiting to decide whether to provide a replacement TCM or order a new one.
• Despite the complexities and conflicting information about previous replacements, the original problem was resolved, and the case was considered closed.

Advice	Diagnostic Step Description
Check for faulty CTS (Coolant Temperature Sensor)	Verify the functionality of the coolant temperature sensor, as it can affect transmission shifting.
Inspect wiring harness for damage	Examine the wiring harness, especially if it was reused during transmission work, for any signs of damage or wear.
Check for bad connections	Carefully inspect and tighten electrical connections, including those on the transmission and TCM, to ensure good contact.
Isolate and test wiring	Isolate the wires from the sensor and computer, apply a load on each wire, and evaluate their ability to carry a load and provide a good ground.
Consider replacing the temp sensor	If the wiring and connections check out, consider replacing the transmission fluid temperature (TFT) sensor, especially if it’s attached to the filter.