P0748: Pressure Control Solenoid A Electrical Malfunction
The P0748 code indicates an electrical fault in the pressure control solenoid 'A' circuit, which is part of the transmission's hydraulic control system. This solenoid regulates line pressure for shifting. The Powertrain Control Module (PCM) detects an abnormal voltage or resistance in the solenoid circuit, often due to wiring issues, a faulty solenoid, or transmission control module problems.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission slipping or stuck in gear
- Reduced fuel economy
2. Most Common Causes
- Faulty pressure control solenoid A
- Open or shorted wiring in solenoid circuit
- Poor electrical connection at solenoid or PCM
- Failed transmission control module (TCM)
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect wiring and connectors for damage, corrosion, or loose pins.
Step 3: Test solenoid resistance with a multimeter (typically 4-6 ohms).
Step 4: Check for battery voltage and ground at solenoid connector with key on.
Step 5: Perform a solenoid actuation test using a scan tool.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0748 can cause harsh shifting, transmission damage, or complete failure. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs vary: DIY solenoid replacement can be $50-$150 for parts; professional labor adds $100-$300. Wiring repairs may be less, while TCM replacement can exceed $500.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.