Transmission Friction Element Slip Detected (P079F)
The P079F code indicates that the transmission control module (TCM) has detected unexpected slip in one or more friction elements (clutches or bands) inside the automatic transmission. This slip can be caused by low fluid level, degraded fluid, worn clutches, or hydraulic circuit issues. If left unaddressed, it can lead to severe transmission damage and failure.
1. Symptoms You Will Notice
- Delayed or harsh gear engagement
- Transmission slipping while driving
- Check Engine Light illuminated
- Reduced fuel economy
2. Most Common Causes
- Low or contaminated transmission fluid
- Worn or burnt clutch packs
- Faulty transmission control solenoid
- Internal hydraulic leak or blockage
3. 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 system test using a professional scanner.
Step 3: Inspect wiring and connectors to the transmission control module and solenoids.
Step 4: Perform a pressure test to identify hydraulic circuit issues.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with a slipping transmission can cause further damage and lead to complete transmission failure. It is best to have it inspected immediately.
How much does it cost to fix?▼
Cost varies widely: a simple fluid change may cost $50-$150, while replacing clutches or solenoids can range from $500 to $2,500 or more.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.