What it means
The transmission control module detects that pressure control solenoid T 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 T is a valve that controls transmission hydraulic pressure when commanded by the transmission control module. P27DA sets when the module detects that solenoid T remains on or open when it should not, potentially applying pressure when the control strategy calls for it to be off.
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 transmission live data before clearing the code, paying attention to commanded solenoid T state and transmission response.
- Inspect solenoid T wiring and connector for shorts, damaged insulation, or poor connections that could keep the circuit energized.
- Use the scan tool's supported output controls, if available, to check whether solenoid T operation follows the module's commands.
- Test the solenoid T control circuit and TCM output for a driver stuck on using the manufacturer's procedure.
- If electrical commands switch correctly but the valve remains on, check solenoid T and its hydraulic passages for sticking or debris.
Common fixes
- Repair wiring or connector faults that keep solenoid T energized.
- Clean or replace solenoid T or its hydraulic feed if debris is preventing the valve from closing.
- Replace pressure control solenoid T if it remains stuck open during testing.
- Repair the TCM output driver if testing confirms it is stuck on.
Can I keep driving?
Limit driving and avoid towing or hard acceleration because an unintended pressure command can cause slipping, harsh shifts, or limp mode. Stop if drive becomes unreliable, as continued use can damage the transmission.
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.