What it means
The transmission control module detects that pressure control solenoid S is stuck on.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Pressure control solenoid S controls a valve that regulates transmission hydraulic pressure. P27D2 sets when the module detects that solenoid S remains on when it should turn off, which can result from a spool stuck open, debris, or a control driver that continues to energize it.
Common causes
Most likely first.
- Solenoid spool stuck in open position
- TCM output driver stuck on
- Carbon or debris buildup preventing free movement
Symptoms
- Transmission warning light may illuminate
- Harsh or delayed shifting
- Slipping or unexpected shifts
- Transmission may enter limp mode
How to diagnose it
- Record freeze-frame data and related transmission codes to identify the conditions when solenoid S was detected stuck on.
- Use scan-tool data to compare the commanded state of solenoid S with available circuit and transmission response data.
- Inspect solenoid S's connector and wiring for damage or shorts that could keep the solenoid energized.
- Check transmission fluid condition and level using the manufacturer's procedure, since contamination can interfere with valve movement.
- Test whether solenoid S responds when commanded off, following vehicle-specific diagnostic information.
- If the electrical command ends but the valve remains on, inspect the solenoid S spool and hydraulic passages for sticking or debris.
Common fixes
- Repair a wiring short or connector fault that keeps solenoid S energized.
- Correct transmission fluid level or condition if it is outside the manufacturer's requirements.
- Remove an identified obstruction from the solenoid S hydraulic passage.
- Clean or replace solenoid S if its spool is stuck open.
- Repair the control module output circuit if testing confirms it continues to command solenoid S on.
Can I keep driving?
Avoid towing and hard acceleration, and stop driving if the transmission slips badly or shifts unpredictably. Solenoid S remaining on can upset hydraulic pressure and damage the transmission if the vehicle is driven under load.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.