OBD-II code · Powertrain (generic)
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.
Is it safe to drive with P079A?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyWorn friction discs in element A
- PossibleLow hydraulic pressure to element A
- PossibleOld ATF lacking friction modifier
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
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 3–12 h
- Emissions test
- Usually unaffected
- Parts involved
- Clutch Pack A, Transmission Fluid
Related codes
- P079BTransmission Friction Element B Slip Detected
- P079CTransmission Friction Element C Slip Detected
- P079DTransmission Friction Element D Slip Detected
- P079ETransmission Friction Element E Slip Detected
- P079FTransmission Friction Element F Slip Detected
- P07A0Transmission Friction Element G Slip Detected
- P07A1Transmission Friction Element H Slip Detected
- P0797Pressure Control Solenoid C Stuck On
- P0798Pressure Control Solenoid C Electrical
- P0799Pressure Control Solenoid C Intermittent
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.