Transmission Friction Element Slip Detected (P079A)
The P079A code indicates that the transmission control module (TCM) has detected unexpected slip in one of the transmission's friction elements, such as a clutch or band. This slip occurs when the actual gear ratio differs from the commanded ratio, often due to worn clutches, low fluid pressure, or internal hydraulic issues. Prolonged driving can cause further damage to the transmission.
01. Most Common Causes
- Low or contaminated transmission fluid
- Worn or burnt clutch packs
- Faulty transmission solenoid or valve body
- Internal transmission leaks or pump failure
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Delayed or harsh shifting
- Transmission slipping or overheating
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Check transmission fluid level and condition; top off or replace if necessary.
Step 2: Scan for additional codes and perform a transmission pressure test.
Step 3: Inspect wiring and connectors to the TCM and solenoids.
Step 4: If no external issues found, internal inspection may be required.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with P079A can cause severe transmission damage. Have it diagnosed immediately.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Repairs can range from a simple fluid change ($100-$200) to a full rebuild ($1,500-$3,500).