Pressure Control Solenoid 'C' Control Circuit High
The P2721 code indicates that the Powertrain Control Module (PCM) has detected a high voltage condition in the control circuit of the pressure control solenoid 'C'. This solenoid regulates hydraulic pressure to the transmission clutches and bands. A high voltage reading suggests a short to power, open circuit, or faulty solenoid, which can lead to improper transmission operation.
01. Most Common Causes
- Faulty pressure control solenoid 'C'
- Short to power in the solenoid control circuit
- Open or damaged wiring/connectors
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission slipping or stuck in gear
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect wiring and connectors for damage, corrosion, or shorts.
Step 3: Test solenoid resistance and compare to manufacturer specs.
Step 4: Check for power and ground at solenoid connector with key on.
Step 5: If wiring and solenoid are good, test PCM output or replace PCM.
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 circuit can cause further transmission damage or unsafe shifting. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, including parts and labor. Solenoid replacement is common; PCM replacement is more expensive.