P0971: Pressure Control Solenoid C Control Circuit High

What it means

Voltage on the pressure control solenoid C control line is above the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

At a glance

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

How it works

Pressure control solenoid C is an electrically operated valve that helps regulate transmission hydraulic pressure. The control module monitors the electrical level in solenoid C’s control circuit and sets P0971 when it detects a level above its expected range. A short to power, open coil, or high-resistance connection can cause this reading, so the code alone does not distinguish among them.

Common causes

Most likely first.

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

Symptoms

• Check engine or transmission warning light on
• Harsh, delayed, or missing shifts
• Possible limp mode (locked in one gear)
• Slipping or shuddering during gear changes

How to diagnose it

1. Record freeze-frame data and check transmission live data for when the high circuit reading occurs and whether solenoid C is being commanded.
2. Inspect solenoid C’s connector seals, pins, and harness for water ingress, corrosion, chafing, pin push-back, or contact with a power wire.
3. With the circuit safely isolated as specified by the manufacturer, check whether solenoid C’s control wire is unintentionally connected to battery power.
4. Measure solenoid C coil resistance and check connector pin fit and circuit continuity against the manufacturer’s specification to identify an open coil or high-resistance connection.
5. If the coil and wiring pass, test the control module’s solenoid C driver and connections using the manufacturer’s procedure.

Common fixes

• Clean and secure corroded solenoid C connector terminals and correct any seal or water-entry issue.
• Repair a solenoid C control wire shorted to power or damaged by chafing.
• Replace pressure control solenoid C if its coil is open or fails testing.
• Repair the control module connection or driver only if circuit testing confirms a module fault.

Can I keep driving?

Avoid towing, hard acceleration, and unnecessary driving if shifts are harsh, delayed, slipping, or the transmission enters limp mode; abnormal pressure control can worsen wear. Stop safely and arrange assistance if the vehicle cannot shift predictably.