P0713 Code: Transmission Fluid Temperature Sensor “A” Circuit High Input

The P0713 diagnostic trouble code (DTC) indicates a malfunction in your vehicle’s Transmission Fluid Temperature (TFT) sensor circuit. This critical sensor monitors the temperature of your transmission fluid and relays this data to your vehicle’s Powertrain Control Module (PCM) or Transmission Control Module (TCM). When the PCM/TCM detects an abnormally high voltage signal from this sensor (typically above 4.6 volts), it triggers the P0713 code.

Understanding the TFT Sensor

The Transmission Fluid Temperature sensor is typically a negative temperature coefficient (NTC) thermistor, meaning its resistance decreases as temperature increases. This sensor is vital for:

• Shift Timing Control: The PCM uses temperature data to adjust shift points, preventing harsh shifts when the transmission is cold
• Torque Converter Clutch Operation: The TCC may not engage properly if temperature readings are incorrect
• Overheating Protection: The PCM can trigger a “limp mode” or reduce engine power if transmission temperatures become dangerously high
• Line Pressure Regulation: Transmission line pressure is often adjusted based on fluid temperature

When your vehicle’s computer detects the P0713 code, you may experience one or more of the following symptoms:

The P0713 code can be triggered by several issues related to the transmission fluid temperature sensor circuit. Here’s a comprehensive breakdown of potential causes:

Technical Explanation of Circuit High Condition

The P0713 code specifically indicates a “Circuit High Input” condition. In automotive electrical terms, this means:

• The PCM is detecting voltage on the TFT signal circuit that is higher than expected for current operating conditions
• Typically, the PCM expects to see a voltage between 0.5V (hot fluid) and 4.5V (cold fluid)
• A P0713 code is set when the voltage remains above approximately 4.6 volts for a predetermined amount of time
• This high voltage reading makes the PCM believe the transmission fluid is extremely cold, even when it’s at normal operating temperature

Proper diagnosis of a P0713 code requires a systematic approach. Here’s our comprehensive diagnostic procedure used by our certified technicians:

Required Tools

• Digital Multimeter (DMM) with temperature probe
• OBD-II Scanner with live data capability
• Vehicle-specific service manual for wiring diagrams
• Backprobe pins or T-pins
• Inspection mirror and flashlight

Step-by-Step Diagnostic Procedure

1. Initial Code Verification
   • Use an OBD-II scanner to confirm P0713 is present and check for additional codes
   • Clear codes and test drive to see if P0713 returns immediately or after specific conditions
   • Note any freeze frame data (engine temp, vehicle speed, etc.) when the code set
2. Transmission Fluid Inspection
   • Check transmission fluid level with engine running and transmission at operating temperature
   • Inspect fluid condition: color, smell, and presence of contaminants
   • Compare fluid temperature to ambient temperature – should be warm after driving
3. Live Data Monitoring
   • Monitor TFT sensor readings with scan tool while driving through various conditions
   • Compare TFT reading to engine coolant temperature (should be similar after warm-up)
   • Look for erratic readings, no change in readings, or consistently high readings
4. Visual Inspection
   • Locate TFT sensor (typically on transmission valve body, case, or inside transmission pan)
   • Inspect wiring harness for chafing, burns, or damage, especially near hot components
   • Check connectors for corrosion, bent pins, or loose connections
5. Sensor Resistance Testing
   • Disconnect electrical connector from TFT sensor
   • Measure resistance across sensor terminals with a multimeter
   • Compare to specifications (typically 1,000-4,000 ohms at room temperature)
   • Test resistance while heating sensor with heat gun (resistance should decrease)
6. Circuit Voltage Testing
   • With sensor connected and ignition ON, backprobe the signal wire
   • Measure voltage – should typically be between 0.5-4.5V depending on temperature
   • A consistently high voltage (above 4.5V) indicates circuit problem
7. Reference Voltage and Ground Verification
   • Check for proper 5V reference voltage at sensor connector with ignition ON
   • Verify sensor ground circuit has continuity to chassis ground
   • Check for voltage drop across ground circuit (should be less than 0.1V)
8. Short to Power Test
   • With sensor disconnected, check for voltage on signal wire with ignition ON
   • If voltage is present, there’s a short to power in the wiring between sensor and PCM

Diagnostic Flow Chart

Once you’ve identified the cause of the P0713 code, follow these detailed repair procedures:

Repairing Wiring Issues

• Identify damaged section of wiring using wiring diagram and visual inspection
• Repair or replace damaged wires using proper automotive-grade wire and connectors
• Use solder and heat shrink tubing for permanent repairs (avoid crimp connectors for sensor circuits)
• Route wiring away from hot components and sharp edges to prevent future damage
• Protect repaired sections with conduit or loom and secure with proper ties

Replacing the TFT Sensor

1. Disconnect negative battery cable for safety
2. Locate TFT sensor (consult service manual for exact location)
3. If necessary, drain transmission fluid into clean container
4. Disconnect electrical connector from sensor
5. Remove old sensor (may require special socket or wrench)
6. Clean sensor mounting area and apply thread sealant if specified
7. Install new sensor with proper torque specification (typically 10-15 ft-lbs)
8. Reconnect electrical connector
9. Refill transmission fluid with correct type and quantity
10. Reconnect battery, clear codes, and perform test drive
11. Verify repair by monitoring live data and ensuring code does not return

Addressing Connector Issues

• Clean corroded connectors with electrical contact cleaner
• Repair bent pins carefully using needle-nose pliers
• Apply dielectric grease to prevent future corrosion
• Replace entire connector if damaged beyond repair

The cost to repair a P0713 code varies significantly depending on the cause, vehicle make/model, and labor rates in your area:

Factors Affecting Repair Cost

• Vehicle Make/Model: Luxury vehicles and those with complex transmission designs typically cost more to repair
• Sensor Location: Sensors inside the transmission pan require more labor to access
• Labor Rates: Vary by region and shop type (dealership vs. independent)
• Additional Repairs: Often other issues are discovered during diagnosis
• Fluid Type: Synthetic and specialty transmission fluids cost more

To prevent P0713 and other transmission-related issues, follow these maintenance guidelines:

Regular Maintenance Schedule

• Check transmission fluid monthly for level and condition
• Change transmission fluid according to manufacturer recommendations (typically 30,000-60,000 miles)
• Use only specified transmission fluid – never substitute unless approved by manufacturer
• Inspect transmission cooling system regularly for leaks or damage
• Address any transmission issues promptly to prevent further damage

Driving Habits to Extend Transmission Life

• Avoid “power braking” (holding vehicle with accelerator while brakes are applied)
• Allow transmission to engage fully before accelerating after shifting from Park to Drive
• Don’t tow beyond your vehicle’s rated capacity
• Avoid frequent hard acceleration, especially when transmission is cold
• Use parking brake on inclines to reduce stress on transmission parking pawl

Early Warning Signs

Watch for these early indicators of potential TFT sensor issues:

• Check Engine Light that comes on intermittently
• Slightly harsh shifts when transmission is warm
• Delayed engagement when shifting from Park to Drive
• Transmission temperature gauge reading inaccurately
• Decreased fuel economy without other explanation