Pressure Control Solenoid C Stuck On
P0797 indicates that the transmission's Pressure Control Solenoid C is stuck in the ON position, preventing proper hydraulic pressure regulation. This fault disrupts transmission shift timing and fluid pressure control, often forcing the vehicle into limp mode to prevent further damage.
What You Might Notice
- Check Engine Light illuminated
- Vehicle enters limp mode or reduced power mode
- Transmission slips during gear shifts
- Transmission overheating
- Decreased fuel economy
- Hard or delayed gear engagement
Most Common Causes
- 1
Defective Pressure Control Solenoid C
The solenoid valve is mechanically stuck in the open position or has failed electrically, preventing it from controlling transmission fluid pressure properly.
- 2
Dirty or contaminated transmission fluid
Degraded or contaminated fluid can cause the solenoid valve to stick or not seal completely, reducing hydraulic pressure control accuracy.
- 3
Clogged transmission filter
A restricted filter reduces overall system pressure and can cause the solenoid to malfunction or trigger false fault codes.
- 4
Faulty wiring or corroded connector at solenoid
Damaged wiring, corroded terminals, or loose connectors prevent proper electrical signals to the solenoid, causing it to remain in an energized state.
How to Diagnose It
- 1
Check Defective Pressure Control Solenoid C — The solenoid valve is mechanically stuck in the open position or has failed electrically, preventing it from controlling transmission fluid pressure properly.
- 2
Check Dirty or contaminated transmission fluid — Degraded or contaminated fluid can cause the solenoid valve to stick or not seal completely, reducing hydraulic pressure control accuracy.
- 3
Check Clogged transmission filter — A restricted filter reduces overall system pressure and can cause the solenoid to malfunction or trigger false fault codes.
- 4
Check Faulty wiring or corroded connector at solenoid — Damaged wiring, corroded terminals, or loose connectors prevent proper electrical signals to the solenoid, causing it to remain in an energized state.
How to Fix It
- 1
Replace transmission fluid and filter
Drain and refill the transmission with OEM-specified fluid and install a new transmission filter to remove contamination that may be causing solenoid malfunction.
- 2
Inspect and clean solenoid connector
Check the wiring harness and connector at Pressure Control Solenoid C for corrosion, damage, or loose pins. Clean or replace the connector if necessary.
- 3
Replace Pressure Control Solenoid C
If the solenoid is stuck or electrically faulty, remove and replace it with an OEM or equivalent replacement solenoid and verify the code clears.
- 4
Inspect transmission valve body and passages
If other fixes fail, have the transmission valve body inspected for sludge buildup or restricted passages that prevent proper pressure regulation.
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