P0713 Transmission Fluid Temperature Sensor "A" Circuit High Input

The P0713 – Transmission Fluid Temperature Sensor "A" Circuit High Input diagnostic trouble code (DTC) indicates that the transmission control module (TCM) has detected an abnormally high electrical signal voltage from the Transmission Fluid Temperature (TFT) Sensor "A" circuit.

The TFT sensor measures the temperature of the transmission fluid and provides this information to the TCM. The controller uses the temperature signal to adjust shift timing, hydraulic pressure, torque converter clutch operation, warm-up strategy, and transmission protection functions.

The important word in this code is “High Input.” In most TFT sensor systems, particularly those using an NTC thermistor, a high circuit voltage usually corresponds to the TCM interpreting the transmission fluid as extremely cold, not extremely hot.

This distinction is important because P0713 is primarily an electrical signal problem. It does not necessarily mean that the transmission fluid is actually too hot.

What Does P0713 Mean?

In simple terms:

The TCM is seeing a TFT sensor circuit voltage that is higher than the expected value.

The basic operation is:

TFT sensor measures fluid temperature → Sensor changes electrical resistance → Circuit voltage changes → TCM interprets the voltage as temperature → Voltage becomes too high → P0713 is stored

On many vehicles, the TFT sensor is an NTC thermistor.

As temperature rises:

Resistance decreases → Signal voltage generally decreases

As temperature falls:

Resistance increases → Signal voltage generally increases

Therefore, a high-input P0713 condition can cause the scan tool to show an unrealistically low transmission temperature.

The exact circuit behavior should always be confirmed with the manufacturer's wiring diagram and specifications.

What Is the Transmission Fluid Temperature Sensor?

The Transmission Fluid Temperature Sensor (TFT) measures the temperature of the transmission fluid.

It may be:

• Integrated into the transmission valve body

• Part of an internal transmission wiring harness

• Mounted in the transmission case

• Integrated into a transmission control assembly

The exact location depends on the transmission design.

The TCM uses TFT information to determine how the transmission should operate at different temperatures.

Why Is Transmission Fluid Temperature Important?

Transmission fluid behaves differently at different temperatures.

Temperature information can be used for:

• Shift timing

• Line pressure control

• Torque converter clutch operation

• Cold-start strategy

• Transmission warm-up

• Overheat protection

• Shift quality adjustments

• Diagnostic monitoring

If the TCM believes the transmission is extremely cold because of a false high-input signal, it may change its operating strategy.

Symptoms of P0713

The symptoms depend on the vehicle and how the TCM responds to the abnormal signal.

Possible symptoms include:

Check Engine Light

The malfunction indicator lamp may illuminate.

Harsh shifting

The transmission may use a different pressure strategy.

Delayed shifting

The TCM may alter shift timing based on the incorrect temperature information.

Abnormal shift behavior

Gear changes may occur at unusual RPMs.

Torque converter clutch problems

TCC engagement may be delayed, modified, or disabled.

Incorrect transmission temperature reading

A scan tool may show an extremely low or unrealistic temperature.

Poor fuel economy

Incorrect transmission temperature information can affect shift and torque converter strategies.

Limp mode

Some vehicles may enter a protective transmission strategy.

Cold-transmission behavior when the transmission is actually warm

The transmission may behave as though it has not reached operating temperature.

What Causes P0713?

Several electrical faults can cause a high TFT circuit input.

Open TFT sensor circuit

An open circuit is one of the most common causes.

If the sensor circuit is open, the TCM may see a high voltage and interpret it as an extremely low temperature.

Disconnected sensor connector

A disconnected connector can produce the same electrical condition as an open circuit.

Broken signal wire

A damaged wire between the TFT sensor and TCM can interrupt the circuit.

Corroded connector terminals

Corrosion can prevent the correct sensor signal from reaching the TCM.

Loose terminal

A terminal with poor contact can create a high-input condition.

Faulty TFT sensor

The sensor may have an internal open circuit.

Damaged internal transmission harness

On some transmissions, the TFT sensor is part of an internal harness.

Short to voltage

The signal circuit may be contacting a higher voltage circuit.

TCM reference-voltage problem

A control-module circuit problem can cause an abnormal sensor input.

TCM fault

The TCM itself may have a defective input circuit, although this should generally be considered only after the sensor and wiring have been tested.

Can a Bad TFT Sensor Cause P0713?

Yes.

The TFT sensor may develop an internal open circuit or resistance value outside its specification.

If the sensor's resistance becomes extremely high, the TCM may interpret the condition as an extremely cold transmission.

However, the sensor should not automatically be replaced without testing the circuit.

Can an Open Circuit Cause P0713?

Yes.

This is one of the most important diagnostic points for P0713.

If the sensor circuit is broken:

TFT sensor → X → TCM

the TCM may see the circuit voltage rise toward its reference voltage.

The result can be:

High input voltage → Extremely low calculated temperature → P0713

This is why P0713 frequently requires a careful inspection of the wiring and connector.

Can a Disconnected Connector Cause P0713?

Yes.

A disconnected TFT sensor connector can create an open circuit.

If the vehicle suddenly develops P0713 after transmission service, wiring work, or connector handling, the connector should be one of the first things inspected.

Can Wiring Cause P0713?

Yes.

Inspect the entire TFT circuit for:

• Broken wires

• Open circuits

• Chafing

• Corrosion

• Loose terminals

• Short to voltage

• Damaged insulation

• Poor terminal contact

A wire can appear intact externally while being broken internally.

Can a Bad Ground Cause P0713?

Depending on the circuit design, yes.

The exact effect depends on whether the TFT circuit uses a dedicated sensor ground or a shared reference circuit.

A missing or poor ground can alter the voltage seen by the TCM.

The correct wiring diagram should be used to determine the circuit configuration.

Can Low Transmission Fluid Cause P0713?

No, not directly.

Low transmission fluid can cause overheating or abnormal transmission operation, but it does not normally create a high electrical input signal from the TFT sensor.

If P0713 is present, the electrical circuit should be investigated.

Does P0713 Mean the Transmission Is Too Hot?

Usually, no.

This is an important distinction.

The code says:

Circuit High Input

It does not mean:

Transmission temperature is too high.

With a typical NTC TFT sensor, a high circuit voltage generally corresponds to a very low calculated temperature.

For example, the scan tool might display a value such as:

-40°C

or another implausibly low temperature.

The exact default value varies by vehicle.

This often points toward an open circuit or disconnected sensor.

Why Might the Scan Tool Show -40°C?

A reading around -40°C / -40°F is commonly used by vehicle electronics as a default or substitute value when a temperature sensor circuit appears open.

If the transmission is physically warm but the scan tool reports approximately -40°C, the technician should strongly suspect:

• Open circuit

• Disconnected sensor

• Broken wire

• Failed sensor

• Connector problem

The exact value and strategy vary by manufacturer.

Can P0713 Cause Harsh Shifting?

Yes.

If the TCM believes the transmission is extremely cold, it may modify:

• Line pressure

• Shift timing

• Torque converter operation

This can result in harder or unusual shifts.

Can P0713 Cause Limp Mode?

Yes, on some vehicles.

If the TCM considers the temperature information unreliable, it may activate a protective strategy.

Possible effects include:

• Limited gear selection

• Modified shift pressure

• Disabled torque converter clutch

• Altered shift strategy

The exact response depends on the transmission.

Can P0713 Affect the Torque Converter?

Yes.

The TCM uses transmission temperature information when controlling the torque converter clutch.

If the temperature signal is incorrect, TCC operation may be altered.

Possible symptoms include:

• Delayed TCC engagement

• TCC not engaging

• Higher cruising RPM

• RPM fluctuations

• Reduced fuel economy

Does P0713 Mean the Transmission Is Bad?

No.

P0713 is primarily an electrical sensor-circuit code.

A mechanically healthy transmission can store P0713 because of a:

• Broken wire

• Disconnected connector

• Failed temperature sensor

• Corroded terminal

• Internal transmission harness problem

Internal transmission damage should not be assumed based on P0713 alone.

How Is P0713 Diagnosed?

The objective is to determine why the TCM is seeing excessive voltage in the TFT circuit.

1. Scan all DTCs

Look for other codes related to:

• Transmission temperature

• Transmission pressure

• Shift solenoids

• Speed sensors

• Gear ratios

• TCM communication

2. Check freeze-frame data

Review:

• Transmission temperature

• Engine temperature

• Vehicle speed

• Engine RPM

• Selected gear

• Battery voltage

3. Check TFT live data

Look at the transmission temperature reported by the TCM.

If the transmission is warm but the scan tool shows an extremely low temperature, investigate the TFT circuit.

4. Inspect the TFT connector

Look for:

• Disconnected connector

• Corrosion

• Bent pins

• Loose terminals

• Oil contamination

• Damaged connector lock

5. Inspect wiring

Check for:

• Open circuits

• Broken wires

• Shorts

• High resistance

• Damaged insulation

6. Measure sensor resistance

If the sensor is accessible, measure its resistance and compare it with the manufacturer's temperature/resistance specifications.

7. Check circuit voltage

Measure the voltage at the sensor and compare it with manufacturer specifications.

8. Check continuity

Verify the electrical connection between the TFT sensor and TCM.

9. Check for short to voltage

A signal wire contacting a voltage source can cause a high-input condition.

10. Test the TCM

If the sensor and wiring are proven correct but the TCM continues to report an abnormally high signal, the TCM input circuit may require further diagnosis.

What Should TFT Temperature Look Like in Live Data?

A healthy temperature reading should generally be physically plausible.

For example, as the transmission warms:

20°C → 35°C → 50°C → 70°C → 85°C

The exact operating temperature varies significantly between vehicles.

A reading such as:

85°C → -40°C

without any physical cooling event is highly suspicious for an electrical problem.

Can a Multimeter Diagnose P0713?

Yes.

A multimeter can be useful for:

• Measuring sensor resistance

• Checking reference voltage

• Checking continuity

• Checking voltage

• Checking for short circuits

However, the manufacturer's specifications are essential because TFT sensor resistance varies by temperature.

Testing a sensor at one temperature without knowing the expected resistance can lead to an incorrect diagnosis.

Can an Oscilloscope Help?

For a typical thermistor-based TFT sensor, an oscilloscope is generally less essential than it is for a speed sensor.

A multimeter and scan tool can often provide sufficient information.

However, an oscilloscope can still be useful for detecting:

• Intermittent voltage changes

• Electrical interference

• Reference-voltage instability

What If P0713 Appears After Transmission Service?

Check the transmission connector and wiring first.

A service procedure may involve:

• Disconnecting the transmission harness

• Removing the valve body

• Moving internal wiring

• Removing a transmission pan

If P0713 appeared immediately after such work, an improperly connected or damaged TFT circuit becomes a strong suspect.

What If P0713 Appears Only When the Vehicle Is Moving?

A loose connector or damaged wire may be affected by:

• Vibration

• Transmission movement

• Harness movement

Monitor TFT live data while carefully inspecting the relevant harness.

What If P0713 Appears When the Transmission Is Hot?

Although P0713 commonly points toward a high electrical input/open circuit, a temperature-dependent sensor or wiring problem is possible.

A sensor may develop an internal open circuit as it heats up.

The vehicle should be tested at the temperature where the fault occurs.

Can P0713 Cause Poor Fuel Economy?

Yes, indirectly.

Incorrect temperature information can change:

• Shift timing

• Torque converter clutch strategy

• Transmission operating pressure

These changes can increase engine RPM and reduce efficiency.

Is P0713 a Serious Problem?

It should not be ignored.

The code may be caused by a relatively simple electrical problem, but incorrect temperature information can affect transmission operation.

If the vehicle is shifting abnormally or entering limp mode, diagnosis should be performed promptly.

Can You Drive With P0713?

If the vehicle is operating normally, a short drive to a repair facility may be possible.

However, avoid prolonged driving if there is:

• Harsh shifting

• Limp mode

• Transmission overheating

• Slipping

• Warning messages

• Major changes in transmission behavior

The actual transmission temperature should also be verified if the vehicle reports a temperature-related warning.

How Is P0713 Repaired?

The correct repair depends on the confirmed fault.

Possible repairs include:

• Replacing the TFT sensor

• Repairing an open wire

• Repairing a shorted wire

• Repairing connector terminals

• Replacing a damaged connector

• Repairing internal transmission wiring

• Restoring the sensor circuit

• Repairing the TCM circuit when properly diagnosed

If the sensor is integrated into an internal transmission harness, access may require transmission-pan or valve-body removal.

Does P0713 Require Transmission Repair?

Not necessarily.

This code is commonly related to the electrical side of the TFT sensor system.

A simple broken wire or disconnected connector can trigger P0713.

Even if the sensor is located inside the transmission, replacing the sensor or internal harness does not necessarily mean that the transmission's mechanical components are damaged.

Common Diagnostic Mistakes

Assuming P0713 means high transmission temperature

The code refers to high electrical input, not necessarily high fluid temperature.

Replacing the TFT sensor immediately

An open circuit or disconnected connector can create the same condition.

Ignoring the wiring

A broken signal wire is a common cause of a high-input condition.

Ignoring a -40°C reading

An implausibly low temperature can be a major clue to an open circuit.

Checking only the sensor

The complete circuit between the sensor and TCM should be tested.

Replacing the TCM too quickly

The sensor, connector, wiring, power/reference circuits, and grounds should be verified first.

P0713 vs. Other TFT Sensor Codes

The related codes describe different electrical conditions:

P0710 – Transmission Fluid Temperature Sensor "A" Circuit

General TFT sensor circuit problem.

P0711 – Transmission Fluid Temperature Sensor "A" Circuit Range / Performance

The temperature signal is outside the expected range or does not correspond to operating conditions.

P0712 – Transmission Fluid Temperature Sensor "A" Circuit Low Input

The TFT circuit voltage is lower than expected.

P0713 – Transmission Fluid Temperature Sensor "A" Circuit High Input

The TFT circuit voltage is higher than expected.

P0714 – Transmission Fluid Temperature Sensor "A" Circuit Intermittent

The TFT signal intermittently becomes unreliable.

How Do You Clear P0713?

The underlying electrical problem should be repaired first.

Then:

Clear the DTC → Check TFT live data → Start the vehicle → Warm up the transmission → Monitor temperature → Road test → Rescan

The temperature value should be physically plausible and should change gradually as the transmission warms.

If the scan tool continues to show an extremely low or otherwise implausible temperature, the TFT circuit requires further investigation.

Final Thoughts on P0713

P0713 – Transmission Fluid Temperature Sensor "A" Circuit High Input indicates that the TCM has detected excessively high electrical voltage in the TFT Sensor "A" circuit.

With the common NTC thermistor design, a high circuit voltage generally means the TCM interprets the transmission as being extremely cold, rather than extremely hot.

The most common areas to investigate are the TFT sensor, connector, open or damaged wiring, sensor circuit voltage, terminals, internal transmission harness, and TCM input circuit.

A particularly useful diagnostic clue is an implausibly low transmission temperature on the scan tool, such as a value around -40°C, while the transmission is actually warm. This strongly suggests an open circuit, disconnected connector, broken wire, or failed sensor, although the exact diagnostic behavior depends on the vehicle.

A practical diagnostic path is:

Scan all DTCs → Check freeze-frame data → Monitor TFT live data → Inspect the sensor connector → Inspect wiring → Check for an open circuit → Measure sensor resistance → Verify circuit voltage → Check for short to voltage → Inspect internal transmission wiring if applicable → Test the TCM circuit → Repair the confirmed fault → Clear the code → Warm up the transmission → Road test and rescan.

Most importantly, P0713 does not automatically mean that the transmission is overheating or mechanically damaged. In many cases, the problem is a relatively straightforward electrical fault in the TFT sensor circuit.