Pressure Control Solenoid C Intermittent
P0799 indicates the transmission control module detected an intermittent electrical signal from the Pressure Control Solenoid C circuit. This solenoid regulates hydraulic pressure for smooth gear shifting, and intermittent faults can cause erratic transmission behavior and potential damage if ignored.
What You Might Notice
- Check Engine Light illuminated
- Transmission enters limp mode or reduced power mode
- Transmission slips or hesitates during gear shifts
- Transmission overheating
- Decreased fuel economy
Most Common Causes
- 1
Defective Pressure Control Solenoid C
The solenoid itself may be failing internally or have intermittent electrical contact, causing inconsistent pressure regulation signals to the transmission control module.
- 2
Corroded or damaged electrical connector
Moisture, corrosion, or loose connections at the solenoid connector can cause intermittent signal loss between the PCM and solenoid.
- 3
Dirty or contaminated transmission fluid and clogged filter
Degraded fluid reduces solenoid responsiveness and can cause varnish buildup that affects solenoid operation, while a clogged filter restricts hydraulic flow.
- 4
Faulty wiring or PCM issue
Damaged wiring harness, corroded terminals, or a defective transmission control module can send or receive intermittent signals to the pressure control solenoid.
How to Diagnose It
- 1
Check Defective Pressure Control Solenoid C — The solenoid itself may be failing internally or have intermittent electrical contact, causing inconsistent pressure regulation signals to the transmission control module.
- 2
Check Corroded or damaged electrical connector — Moisture, corrosion, or loose connections at the solenoid connector can cause intermittent signal loss between the PCM and solenoid.
- 3
Check Dirty or contaminated transmission fluid and clogged filter — Degraded fluid reduces solenoid responsiveness and can cause varnish buildup that affects solenoid operation, while a clogged filter restricts hydraulic flow.
- 4
Check Faulty wiring or PCM issue — Damaged wiring harness, corroded terminals, or a defective transmission control module can send or receive intermittent signals to the pressure control solenoid.
How to Fix It
- 1
Inspect and clean electrical connector
Locate the Pressure Control Solenoid C connector and inspect for corrosion, moisture, or loose pins. Clean with electrical contact cleaner and ensure a tight connection. This often resolves intermittent electrical faults.
- 2
Change transmission fluid and filter
Drain old transmission fluid and replace with manufacturer-specified fluid and a new transmission filter. Contaminated fluid can cause solenoid stiction and erratic operation.
- 3
Replace Pressure Control Solenoid C
If connector cleaning and fluid service do not resolve the issue, replace the defective solenoid. This is the most common fix for intermittent P0799 codes.
- 4
Repair or replace wiring and connectors
If solenoid replacement does not resolve the code, inspect the entire wiring harness from the PCM to the solenoid for damage, corrosion, or broken strands. Repair or replace damaged sections.
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