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P079A Powertrain

Transmission Friction Element A Slip Detected

Friction element A (the first clutch or band in the gear matrix) shows measurable slip while it should be fully engaged. Detected by comparing input/output speed sensors against the commanded gear ratio. Slip means the element cannot transmit full torque — risk of glazing the friction surfaces.

Affected components

  • Clutch pack a
  • Transmission fluid

Common causes

  • High likelihood: Worn friction discs in element A
  • Medium likelihood: Low hydraulic pressure to element A
  • Medium likelihood: Old ATF lacking friction modifier

Possible symptoms

  • Check engine or transmission warning light on
  • Harsh, delayed, or missing shifts
  • Possible limp mode (locked in one gear)
  • Slipping or shuddering during gear changes

Diagnostic notes

  • The malfunction indicator lamp may illuminate

Related codes

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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