A pressure control solenoid is designed to maintain the hydraulic pressure needed to activate a particular clutch pack or transmission band. If the computer detects a high voltage signal on the pressure control solenoid control circuit, a P2721 DTC will be saved in the ECU memory.
How Serious is the Code?
The P2721 OBDII diagnostic trouble code is extremely serious. When a P2721 DTC is set, the computer will command maximum line pressure, stop the torque converter clutch from working, and some vehicles will go into a limp mode where only 1-2 forward gears are available. This situation will cause extra wear on internal components and prevent the vehicle from performing as intended.
Symptoms of a P2721 include:
- Harsh, delayed or erratic shifts
- Slipping in-and-out of gear
- Getting stuck in gear
- Vehicle won’t move when in gear
- Engine stalls
- Reduced fuel economy
- Transmission overheats
- Limp mode
- Low transmission fluid
- Dirty transmission fluid / filter
- Frayed wiring / damaged connectors
- Failed pressure control solenoid
- Failed transmission pump
- Pressure blockage
- Valve body issue
- TCM or ECU failure
How to Diagnose the Code?
The first thing that should be done when diagnosing a P2721 OBD2 trouble code, is to check the level and condition of the transmission fluid. If it’s too low or too dirty, then hydraulic pressure issues can result. The condition of the wiring and connectors on the transmission wiring harness should also be assessed for signs of damage and corrosion. Should no issues be found by this point, pressure control solenoid and valve body should be inspected and tested. TCM programming may also be to blame.
What Repairs Will Fix P2721?
- Changing the fluid and filter
- Replace faulty pressure control solenoid
- Repair or replace a faulty transmission pump
- Repair defective transmission valve body
- Install a remanufactured valve body
- Transmission flush to clean passages
- Cleaning corrosion from connectors
- Repairing or replacing wiring
- Flashing or replacing PCM
- P2717 – Pressure Control Solenoid D Intermittent
- P2718 – Pressure Control Solenoid D Ctrl Circ / Open
- P2719 – Pressure Control Solenoid D Ctrl Circ Range/Perf
- P2720 – Pressure Control Solenoid D Ctrl Circ Low