Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car's computer is confused because it thinks the temperature of the transmission fluid and the transmission control module (TCM) don't match up like they should.
This code indicates a discrepancy between the transmission fluid temperature and the temperature measured by the Transmission Control Module (TCM).
The P1779 OBD-II code is triggered when the Powertrain Control Module (PCM) detects that the temperature readings of the transmission fluid and the TCM are not correlating as expected. This could be due to sensor issues or wiring problems.
• Check Engine Light is on
• Transmission may overheat
• Poor transmission performance
• Erratic shifting
• Faulty transmission fluid temperature sensor
• Faulty TCM temperature sensor
• Wiring issues or poor connections
• PCM or TCM malfunction
PCM: Powertrain Control Module
TCM: Transmission Control Module
• Scan the vehicle for additional codes.
• Inspect the wiring and connectors for damage.
• Test the transmission fluid temperature sensor.
• Test the TCM temperature sensor.
• Replace faulty temperature sensors.
• Repair or replace damaged wiring.
• Reprogram or replace the PCM/TCM if necessary.
• Clear codes and test drive the vehicle.
• OBD-II scanner
• Multimeter
• Thermometer
• Basic hand tools
$150 - $500
Moderate
• Honda Accord
• Toyota Camry
• Ford F-150
• Regularly check transmission fluid levels.
• Ensure proper maintenance of transmission.
• Inspect wiring and connectors periodically.
Sensor Issue
• Address the issue promptly to avoid transmission damage.
• Consult a professional mechanic for accurate diagnosis.
Check with your vehicle manufacturer for warranty coverage on transmission components.
This code has been commonly reported in vehicles with high mileage or those with previous transmission issues.
Moderate – Addressing this issue can prevent further transmission damage.
Ignoring this code may lead to transmission failure, which can be a safety hazard.
• Engine at operating temperature
• Vehicle in park or neutral
The transmission fluid temperature sensor is typically located in the transmission oil pan or near the transmission cooler lines.
Q: Can I drive with a P1779 code?
A: It's not recommended to drive for extended periods with this code as it can lead to transmission damage.
Q: How do I reset the P1779 code?
A: After repairs, use an OBD-II scanner to clear the code and verify it does not return.
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