What it means
An electrical fault on the pressure control solenoid A circuit - typically open or short to ground or supply.
At a glance
- Usually lights the check-engine light
How it works
Pressure control solenoid A is an electrically controlled valve that regulates hydraulic flow in the transmission. The module sets P0748 when it detects an electrical fault in solenoid A’s circuit, such as an open or a short to ground or supply. It may use a fallback strategy, causing abnormal shifts or a restricted gear.
Common causes
Most likely first.
- Open or short in pressure control solenoid A wiring
- Failed solenoid coil
- Poor connector contact or corrosion
- Fault in the solenoid driver circuit
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
- Record freeze-frame data and scan transmission codes and live data to confirm the fault is associated with pressure control solenoid A.
- Inspect solenoid A’s connector and harness for corrosion, loose pins, fluid intrusion, chafing, or a shorted section.
- With the circuit disconnected as specified by the manufacturer, test solenoid A coil continuity against the manufacturer's specification.
- Check solenoid A wiring for opens and shorts to ground or supply using the wiring diagram and manufacturer's procedure.
- If the solenoid and harness pass, test the transmission module driver circuit according to the manufacturer's diagnostic steps.
Common fixes
- Clean and secure solenoid A’s connector or replace corroded terminals.
- Repair open, shorted, or chafed wiring in solenoid A’s circuit.
- Replace pressure control solenoid A if its coil is out of specification.
- Repair the module driver circuit if testing confirms the module is not controlling the solenoid correctly.
Can I keep driving?
If the transmission shifts normally, limit driving to a short trip for repair and avoid towing or demanding acceleration. Do not continue if it slips, loses a gear, or shifts harshly, because damage can escalate.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.