P0748 means the transmission control module has detected an electrical fault — an open circuit, a short, or a wiring problem — in the circuit for Pressure Control Solenoid A, which regulates the hydraulic pressure that controls how firmly the transmission’s clutches apply during a shift. This joins P0740 and P0715 as part of the same broad family of transmission solenoid and sensor codes on this site, and because this specific code is electrical rather than a mechanical performance fault, wiring and connectors are the first place to look before assuming the solenoid itself has failed.
What Does P0748 Mean?
Pressure Control Solenoid A is one of several solenoids inside an automatic transmission that the control module uses to precisely regulate hydraulic fluid pressure, which in turn determines how firmly the internal clutch packs engage during a shift. P0748 specifically flags an electrical problem with that solenoid’s circuit — distinct from a code that would indicate the solenoid is electrically fine but not producing the expected pressure change. That electrical framing matters diagnostically, since it points first toward wiring, connectors, and the solenoid’s own coil rather than a purely hydraulic or mechanical cause.
Common Symptoms
- Harsh, delayed, or erratic shifting
- The transmission stuck in a single gear (a protective fail-safe mode) — see our car stuck in limp mode guide
- Check engine light on
- A feeling of the transmission slipping — see our transmission slipping symptoms guide
- Overheating transmission fluid in some cases, since incorrect pressure regulation can increase internal friction and heat
Common Causes, Most Likely First
- A damaged, chafed, or corroded wiring harness connecting to the solenoid — the most common cause of any code specifically framed as “electrical” rather than a performance fault.
- A loose or corroded connector at the solenoid itself or along the harness.
- A failed solenoid coil, open or shorted internally, requiring the solenoid to be replaced rather than repaired.
- Contaminated or very low transmission fluid allowing debris to interfere with the solenoid’s electrical connection point inside the transmission, though this is less direct than a pure wiring fault.
- A transmission control module (TCM) fault, less common, where the module itself isn’t properly driving the solenoid circuit.
How to Diagnose It
- Check transmission fluid level and condition first — see our how to check transmission fluid guide — since fluid that’s very low or badly contaminated is worth ruling out before chasing wiring.
- Inspect the wiring harness and connector to the solenoid for visible damage, chafing, or corrosion, which a shop can pinpoint with a wiring diagram specific to your transmission.
- Test the solenoid’s resistance with a multimeter against the manufacturer’s specification to confirm whether the coil itself has failed.
- Check for other stored transmission codes alongside P0748, since a pattern involving multiple solenoids points more toward a fluid or TCM issue than a single failed component.
Never work under a vehicle supported only by a jack. Use axle stands on firm, level ground, chock the wheels that stay down, and leave the car in gear or Park with the handbrake on. A jack lifts; stands hold.
Possible Fixes
| Cause | Fix | Typical cost |
|---|---|---|
| Damaged wiring/connector | Repair or replace the affected wiring | $150 – $350 |
| Failed solenoid coil | Replace the solenoid | $200 – $450 |
| Contaminated transmission fluid | Fluid and filter service | $150 – $300 |
| TCM fault | Module diagnosis/replacement | $300 – $600 |
Can I Keep Driving With This?
Short trips only — if the transmission has entered a protective fail-safe mode limiting it to one gear, avoid highway driving and get it inspected promptly. See our car stuck in limp mode guide for the general reasoning behind why continuing to drive in that state isn’t advisable for very long.
When to See a Mechanic
Reasonably soon, sooner if the transmission has noticeably changed its shifting behavior or entered a limited gear range. More in our transmission section.
Frequently Asked Questions
What does P0748 mean?
It means there’s an electrical fault — an open circuit, short, or wiring problem — in the circuit for Pressure Control Solenoid A, which regulates hydraulic pressure controlling clutch engagement during shifts.
What’s the most common cause of P0748?
Damaged, chafed, or corroded wiring connecting to the solenoid is the most common cause, since this code specifically flags an electrical fault rather than a performance issue.
Is P0748 related to P0740 or P0715?
They’re part of the same broad family of transmission solenoid and sensor codes, though each targets a different specific component — P0748 is electrical and specific to Pressure Control Solenoid A.
Is it safe to drive with a P0748 code?
Short trips only — if the transmission has entered a limited-gear fail-safe mode, avoid highway driving and get it inspected promptly rather than continuing to drive normally.
How much does it cost to fix P0748?
Often $150–$350 for a wiring repair, up to $450 if the solenoid itself needs replacement.
