P079A — 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.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Clutch pack a
- Transmission fluid
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Worn friction discs in element A
- Low hydraulic pressure to element A
- 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
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
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.