Fix P0711: Mechanic’s solutions that WORKED

The P0711: Transmission Fluid Temperature Sensor Circuit Range/Performance code indicates that the transmission fluid temperature sensor is reporting readings that are out of the expected range or is performing erratically. This sensor monitors the temperature of the transmission fluid, which is critical for the transmission’s proper operation. When the sensor detects a reading that’s too high, too low, or fluctuating unexpectedly, it triggers this fault code.

P0711 quick overview

Meaning	P0711: Transmission Fluid Temperature Sensor Circuit Range/Performance
Is it serious?	This code can be serious as it may affect the transmission’s performance and longevity.
Possible causes	– Faulty transmission fluid temperature sensor – Damaged or disconnected wiring to the sensor – Corrosion or poor connections in the sensor’s circuit – Faulty Engine Coolant Temperature (ECT) sensor affecting readings – Internal transmission issues affecting temperature – Electrical problems in the vehicle, like grounding issues
How to diagnose?	Check Sensor and Wiring: Inspect the transmission fluid temperature sensor and its wiring for damage, disconnection, or corrosion. Measure Sensor Resistance: Perform an ohm test on the sensor to check if it’s within the specified resistance range. Compare ECT and IAT Readings: Ensure Engine Coolant Temperature and Intake Air Temperature readings are consistent and accurate. Review TSBs and Recalls: Look for any Technical Service Bulletins or recalls related to the P0711 code for the specific vehicle. Check Vehicle History: Investigate any history of towing or accidents that might have affected the transmission. Inspect Battery and Grounds: Verify the battery voltage and check all ground connections for issues. TCM Software Update: Consider updating or reflashing the Transmission Control Module if applicable. Replace Wiring Harness: If all else checks out, consider replacing the transmission wiring harness.

How to fix P0711 – learn from mechanics

I looked into P0711 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: Saturn

Vehicle Information: 1997 Saturn SL2 1.9L

Issue + Repair History:

• Intermittent transmission DTC P0711 for transmission fluid temperature.
• Scan tool shows normal temperature readings.
• Vehicle returned by customer with the same issue shortly after.
• Additional scan shows DTC stored but no abnormal data.
• TSB for “MIL on w/DTC P0711, Set after flat tow” mentioned, but no recent towing known.

Other OBD2 Codes + Test Results:

• DTC P0711 – Transmission Fluid Temperature Sensor Circuit Range/Performance.
• Transmission fluid temperature ranged from 118°F to 178°F during test drive.

Suggestions to Fix Issue:

• Check the coolant temperature sensor for cracks, as it’s used for reference.
• Ensure correct fluid level in the transmission.
• Inspect the transmission temperature sensor for damage or cracks.
• Consider the possibility of the vehicle being flat towed, as per TSB.

Final Fix:

• The issue was related to the vehicle being used as a ‘tow dinghy’ behind a motorhome.
• Towing the vehicle flat caused the transmission temperature to rise.
• The ECT and IAT being cold while the transmission was hot triggered the code.
• Cleared the codes and resolved the issue by addressing the flat towing condition.

Case #2: Hyundai

Vehicle Information: 2001 Hyundai Elantra GLS 2.0L

Issue + Repair History:

• Customer reported erratic transmission shifts when the Check Engine Light (CEL) is on.
• Code P0711 was found in history.
• Replaced transmission temperature sensor and fluid with SP-III fluid after initial test showed the sensor was out of spec.
• Vehicle returned two days later with the same issue and code P0711.

Other OBD2 Codes + Test Results:

• Code P0711 – Transmission Fluid Temperature Sensor Circuit Range/Performance.

Suggestions to Fix Issue:

• Check the coolant temperature sensor for cracks, as it could affect readings.
• Inspect the transmission temperature sensor wiring and connectors for damage or corrosion.
• Check the vehicle with a different scan tool for accurate code readings.
• Consider the possibility of an intermittent issue in the valve body solenoid harness.
• Verify sensor voltage and compare during CEL on and off states.
• Sweep test or wiggle test the Throttle Position Sensor (TPS) for erratic shifts.

Final Fix:

• Problem was related to the input speed sensor reading incorrectly, though it never set a code.
• Input speed was found to be erratic during a test drive.
• Replaced the input speed sensor, which resolved the shifting issue and code P0711.

Case #3: Saturn

Vehicle Information: 1997 Saturn SL2 1.9L

Issue + Repair History:

• Service Engine Soon lamp returns at startup after clearing with transmission temperature sensor (TFT sensor) wiring connected, showing code P0711.
• The issue takes a few minutes of driving to reappear with the connector disconnected.
• Replaced transmission temperature sensor and ran through over 10 warm-up cycles.
• The coolant temperature sensor (ECT) readings were normal.

Other OBD2 Codes + Test Results:

• P0711 – Transmission Temp Sensor Range.
• Reference voltage: 5.2V.
• Ground: Varies.

Suggestions to Fix Issue:

• Check for possible damage or issues with the Engine Coolant Temperature (ECT) sensor.
• Inspect the wiring and connectors for the TFT sensor, especially for potential ground issues.
• Consider the possibility of an aftermarket accessory affecting the TFT sensor ground.

Final Fix:

• The issue remained unresolved as the customer did not return for further testing.
• It was suggested that checking the sensor grounds might be the likely cause of the problem.

Case #4: Chevrolet

Vehicle Information: 2007 Chevrolet Equinox LT 3.4L

Issue + Repair History:

• Intermittent traction light coming on.
• Codes P1779 (engine torque delivery to TCM signal) and P0711 (trans temp sensor) present.
• The transmission temperature sensor includes a wire harness costing over $700.
• The vehicle was sent for a TCM reflash based on a TSB related to these issues.

Other OBD2 Codes + Test Results:

• P1779
• P0711

Suggestions to Fix Issue:

• Address P0711 first, as a software issue in the TCM may cause this condition.
• TSB indicates reprogramming of the TCM is required.
• Do not replace the internal transaxle wiring harness to correct P0711 code.

Final Fix:

• The TCM was reflashed as per the TSB.
• After the reflash, the customer reported no more trouble.

Case #5: Kia

Vehicle Information: 2008 Kia Spectra SX 2.0L

Issue + Repair History:

• Hard shifts and getting stuck in 2nd gear, likely in safety mode.
• Scanned car and found codes P0755 (solenoid B underdrive malfunction), P0711 (temperature sensor), and P0700.
• Replaced solenoid B and TCM but issue persisted.
• Observed possible damage to the temperature sensor.
• Noted discrepancy in tachometer reading between the dashboard and data list.

Other OBD2 Codes + Test Results:

• P0755
• P0711
• P0700

Suggestions to Fix Issue:

• Clean MAF sensor and throttle body.
• Check alternator and charging system.
• Inspect ribbon wires linking the transmission main connector to the solenoids for dry soldered joints.
• Review battery voltage and grounds to affected systems.
• Ensure the VIN is correct for accurate diagnosis.

Final Fix:

• Replaced both electrical ribbons in the valve body.
• After replacement, the vehicle drove smoothly, and the customer was satisfied.

Advice	Diagnostic Step
Check Wiring and Connectors	Inspect the wiring and connectors for the transmission temperature sensor for any signs of damage, corrosion, or loose connections.
Test Temperature Sensor	Conduct an ohm test on the transmission fluid temperature sensor to ensure it falls within the specified resistance range.
Inspect Coolant Temperature Sensor	Check the coolant temperature sensor as it might affect the transmission temperature readings.
Verify ECT and IAT Readings	Ensure that the Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) sensors are providing accurate readings, as discrepancies can trigger P0711.
Consider TSBs and Recalls	Look up any Technical Service Bulletins (TSBs) or recalls that might be related to the P0711 code for specific make and model.
Inspect for Physical Damage	Look for any physical damage to the sensor or surrounding components, especially if the vehicle has a history of towing or accidents.
Ensure Correct VIN	Make sure the correct Vehicle Identification Number (VIN) is used for accurate diagnosis and part selection.
Review Battery and Ground Connections	Check the battery voltage and ground connections, as electrical issues can contribute to the code.
Reflash or Update TCM	If applicable, reflash or update the Transmission Control Module (TCM) software as per manufacturer’s guidelines.
Replace Transmission Wiring Harness	If the sensor and other components are functioning correctly, consider replacing the transmission wiring harness.

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