GM OBD Trouble Code 79

Transmission fluid over temperature

The ECM monitors the automatic transmission fluid temperature via the transmission fluid temperature sensor. If the transmission fluid reaches a predetermined limit, code 79 will be set.

Fault Code Description

  • 79 - Transmission fluid over temperature


  • Transmission shifts may become more firm in an attempt to avoid slippage.

Common Problems

  • Low transmission fluid level
  • Transmission slipping

No comments yet...

Sign in to comment

Related Questions

See what others have asked about this, or visit the Questions page to ask your own question.
What type of fluid goes into the transmission
While towing a load it will sometimes dump transmission fluid