Pressure Control Solenoid 'A' Control Circuit High
The P0971 code indicates that the Powertrain Control Module (PCM) has detected a high voltage condition in the control circuit of the pressure control solenoid 'A'. This solenoid regulates hydraulic pressure to the transmission clutches and bands for smooth shifting. A high voltage reading typically points to a short to power, open circuit, or faulty solenoid, which can cause erratic shifting, harsh engagement, or transmission slippage.
01. Most Common Causes
- Faulty pressure control solenoid 'A'
- Short to power in the solenoid control circuit
- Open or high resistance in the wiring or connector
- Damaged PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifting
- Transmission slipping or stuck in gear
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the transmission wiring and connector for damage, corrosion, or loose pins.
Step 3: Test the solenoid resistance with a multimeter (typically 4-6 ohms).
Step 4: Check for voltage at the solenoid connector with key on (should be battery voltage on one pin).
Step 5: If wiring and solenoid are good, test PCM output or replace PCM as last resort.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a high voltage condition can cause further transmission damage or erratic shifting, potentially leaving you stranded.
How much does it cost to fix?▼
Repair costs vary from $150 to $400, including parts (solenoid $50-$150) and labor (1-2 hours at $100-$150/hr). PCM replacement can exceed $1000.