P27C8: Pressure Control Solenoid P Control Circuit High

What it means

The control circuit for pressure control solenoid P is reporting a high electrical condition.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The transmission control module uses the Pressure Control Solenoid P circuit to regulate hydraulic pressure. This code sets when the circuit signal is electrically high; a short to battery voltage, an open solenoid coil, or poor contact at corroded pins can leave the circuit above its expected level.

Common causes

Most likely first.

1. Control wire shorted to B+
2. Open solenoid coil
3. Connector pins corroded - high contact resistance

Symptoms

• Transmission warning light may illuminate
• Harsh or delayed shifting
• Transmission may enter limp mode

How to diagnose it

1. Record freeze-frame data and scan for related circuit codes that may point to a shared harness or module issue.
2. Inspect the Solenoid P wiring for damage that could let the control wire contact battery voltage, and check the connector for corrosion or loose pins.
3. Measure Solenoid P coil resistance and compare it with the manufacturer’s specification to identify an open coil.
4. With the circuit isolated as directed, test the control wire for a short to battery voltage and check connector continuity.
5. If the solenoid and wiring pass, verify the module output using the manufacturer’s diagnostic procedure.

Common fixes

• Repair a control wire that is shorted to battery voltage.
• Clean and secure corroded or loose Solenoid P connector pins.
• Replace Pressure Control Solenoid P if its coil is open.
• Repair the control module circuit only if testing confirms it is producing the high signal incorrectly.

Can I keep driving?

Keep driving to a minimum because the transmission may shift harshly or enter limp mode. Avoid towing and stop if the vehicle slips, loses drive, or cannot shift reliably.