What Does P079F Mean?
The TCM has detected slippage in transmission friction element F. This friction element — either a clutch pack or band — is not providing adequate torque transfer capacity. The TCM monitors gear ratios via shaft speed sensors and has determined that element F is allowing slip beyond acceptable tolerances during its commanded engagement.
Safety Warning
Friction element slip compromises reliable power delivery. The vehicle may lose traction or power unexpectedly. Drive only at low speeds to a repair shop. Do not tow, haul, or drive on highways. Continued driving accelerates internal damage.
Common Causes
35%
Worn friction element F clutch discs or band surface
25%
Low or degraded transmission fluid
15%
Hydraulic seal failure in element F apply circuit
15%
Valve body or solenoid issue reducing apply pressure
10%
Transmission cooler restriction causing overheating and fluid degradation
Diagnostic Steps
1
Identify the gear ranges where friction element F is applied using the manufacturer's clutch apply chart.
2
Compare calculated gear ratios (from speed sensors) to expected ratios in those gear ranges to quantify slip.
3
Check and correct transmission fluid level and quality.
4
Monitor transmission temperature during driving — if it exceeds 240F, address cooling issues first.
5
Perform line pressure testing in the affected gear positions.
6
If hydraulic system is functioning correctly, internal transmission repair is required for the worn friction element.
Estimated Repair Cost
$300 - $3,500
Parts + labor, varies by vehicle and location
The TCM has detected slippage in transmission friction element F. This friction element — either a clutch pack or band — is not providing adequate torque transfer capacity. The TCM monitors gear ratios via shaft speed sensors and has determined that element F is allowing slip beyond acceptable toler...
The most common cause of P079F (Transmission Friction Element "F" Slip Detected) is: Worn friction element F clutch discs or band surface
Typical repair costs for P079F range from $300 to $3,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Friction element slip compromises reliable power delivery. The vehicle may lose traction or power unexpectedly. Drive only at low speeds to a repair shop. Do not tow, haul, or drive on highways. Continued driving accelerates internal damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P079F to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
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