Transmission · Powertrain · generic (SAE-defined)
P0748: Pressure Control Solenoid "A" Electrical
P0748 means the transmission computer has found an electrical problem, such as an open, short, or out-of-range current, in the circuit for pressure control solenoid A.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0748 sets
The powertrain or transmission control module (PCM/TCM) controls the pressure control solenoid (PCS) with a varying current and monitors the circuit for electrical integrity. If the measured current or voltage indicates an open, short to ground, or short to power, the module sets P0748. It often responds with a failsafe strategy that commands high line pressure. Electrical limits and failsafe behavior are manufacturer-specific.
Common causes of P0748
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Failed pressure control solenoid coil
- Damaged or corroded transmission connector
- Open or shorted wire between module and transmission
- Faulty internal transmission harness
- Low system voltage or poor module ground
- PCM/TCM driver failure
P0748 symptoms
- Check engine light on
- Very firm or harsh shifts
- Transmission held in a single gear (limp mode)
- Delayed engagement
- Possible transmission warning message
How P0748 is diagnosed
- Scan for all codes, including voltage and communication codes, and record freeze frame.
- Check battery voltage and charging system output.
- Inspect the transmission harness and connector for damage, corrosion, or fluid intrusion.
- Measure solenoid resistance at the case connector and compare to specification.
- Check circuit continuity and look for shorts to ground or power back to the module.
- Verify module powers and grounds before considering module replacement.
Typical fixes for P0748
- Repair wiring or connector problems
- Replace the pressure control solenoid
- Replace the internal transmission harness
- Correct charging or ground faults
- Replace or reprogram the PCM/TCM if confirmed faulty
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Manufacturer notes
Ford commonly calls this the electronic pressure control (EPC) solenoid. Solenoid letter assignments vary by manufacturer; check factory service information.
Related codes & warning lights
P0748 FAQ
What does code P0748 mean?
P0748 means the transmission computer has found an electrical problem, such as an open, short, or out-of-range current, in the circuit for pressure control solenoid A. The standard definition is "Pressure Control Solenoid "A" Electrical."
Can I drive with a P0748 code?
Only gently and briefly. Many vehicles default to maximum line pressure or a limp mode when this code sets, which causes harsh shifts and limited gears, so get it checked promptly.
Why does my transmission shift so hard with P0748?
Many transmissions are designed to run maximum line pressure when they lose control of the pressure solenoid. This protects the clutches from slipping but makes every shift firm.
Is P0748 more likely wiring or the solenoid?
Either is common. Because it is an electrical code, a resistance test of the solenoid and a careful harness inspection usually narrow it down.
Keep researching
More transmission codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.