What it means
The transmission control module detects an intermittent fault associated with pressure control solenoid S.
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 regulates transmission hydraulic pressure in response to electrical commands from the transmission control module. P27D4 sets when the module detects that the solenoid S circuit fault comes and goes, rather than remaining continuously present.
Common causes
Most likely first.
- Solenoid connector not fully seated
- Coil resistance drifts with temperature
- Connector with intermittent contact under vibration
Symptoms
- Transmission warning light may illuminate
- Intermittent harsh or delayed shifting
- Transmission may intermittently enter limp mode
How to diagnose it
- Record freeze-frame data and check the conditions when the intermittent solenoid S fault occurred, including transmission temperature and related codes.
- Inspect the solenoid S connector for incomplete seating, corrosion, loose terminals, or signs of movement.
- Check the harness for damage, then gently move it while monitoring available solenoid S circuit data for dropouts.
- Measure solenoid S coil resistance when cold and again when warm, comparing both readings with the manufacturer's specification.
- Check connector terminal tension and control-wire continuity while gently moving the harness to expose intermittent contact.
- If the coil and wiring remain stable, compare commanded solenoid S operation with scan-tool data under the conditions recorded in freeze-frame.
Common fixes
- Fully seat the solenoid S connector and secure it against vibration.
- Clean or repair loose or corroded connector terminals.
- Repair wiring that loses continuity when moved or vibrated.
- Replace solenoid S if its coil resistance changes outside the manufacturer's specification as it warms.
Can I keep driving?
Limit driving if harsh or delayed shifts or limp mode come and go, and avoid towing or heavy acceleration until the fault is resolved. The intermittent solenoid S problem can return suddenly and disrupt pressure control, risking poor shifting or transmission damage.
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.