P0748 — Pressure Control Solenoid A Electrical

OBD2 code P0748 flags a problem with the automatic transmission control (pressure control solenoid a electrical). Short, gentle driving to a shop is usually possible. Common culprits: valve body wear, faulty transmission speed sensor, wiring or connector faults in the valve body harness.

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0748 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the automatic transmission control for damage, corrosion, chafing or poor contact.
Subsystem check Check transmission fluid level and condition — dark, burnt fluid points to internal wear.
Subsystem check Read transmission-specific codes and live data (solenoid states, input/output speed) with a capable scanner.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0748 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0748 (parts and labor, USD, independent shop rates): Transmission fluid service: $150–$350; Replace a shift solenoid: $300–$800; Transmission rebuild or replacement: $2,500–$5,500; Valve body repair or replacement: $700–$1,500. Overall, fixing P0748 usually costs between $150 and $5,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Is it safe to drive with P0748?

Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

How do I diagnose P0748 myself?

Start with a scan: confirm P0748, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the automatic transmission control, and verify the suspect component against live data before buying parts.

Will P0748 clear itself?

Sometimes P0748 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What does OBD2 code P0748 mean?

What are the symptoms of P0748?

Drivers most often notice: slipping between gears, harsh or delayed shifting, shuddering at highway speed, transmission stuck in one gear (limp mode).

Your scan tool is pointing at one of the transmission control system's pressure regulation components. P0748 flags an electrical fault inside the automatic transmission — specifically the circuit that controls Pressure Control Solenoid A. Because this code lives in the powertrain category, it affects the engine and transmission management system together, which is why you may notice driveability changes alongside the check engine light.

The transmission control module watches this solenoid's operation every time you drive. It compares the actual electrical signal against factory-calibrated parameters, and if the reading strays outside acceptable limits for long enough across multiple drive cycles, the module logs P0748 and illuminates the dashboard warning. The stored freeze frame data captures engine speed, load, temperature, and vehicle speed at that exact moment — invaluable information when you're tracing what actually happened.

The fix depends entirely on what caused the solenoid circuit to go out of range, which is why systematic diagnosis matters before spending money on parts.

Typical Symptoms

When Pressure Control Solenoid A fails to regulate transmission line pressure correctly, the gearbox cannot manage gear transitions properly. Watch for these warning signs:

Gear slipping during acceleration or when climbing hills
Shifts that feel harsh, jerky, or noticeably delayed compared to normal
A vibration or shuddering sensation, especially at highway cruising speeds
Transmission locked into a single gear with no upshifts or downshifts (limp-home mode)
Complete loss of forward or reverse movement in severe cases
Erratic or unpredictable shift timing that varies between driving sessions

Common Causes

Several conditions can trigger P0748, ranging from simple fluid issues to internal transmission damage:

Low or contaminated transmission fluid restricting hydraulic pressure
Worn valve body passages or worn pressure regulation components
Damaged, corroded, or loose wiring connectors in the transmission harness
Failed Pressure Control Solenoid A itself
Internal mechanical wear inside the transmission (clutch plates, torque converter)
Faulty transmission input or output speed sensor affecting control logic

Diagnostic Procedure

Follow a logical sequence to isolate the root cause without replacing good parts:

Connect an OBD2 scanner, record P0748 and any other stored codes, then save the freeze frame data — this snapshot reveals what conditions triggered the fault.
Look up any additional diagnostic trouble codes and search manufacturer TSB databases for known fixes related to your vehicle's make, model, and model year.
Inspect the transmission wiring harness and electrical connectors for damaged insulation, corrosion, bent pins, or loose connections at the valve body.
Check transmission fluid level and condition — burnt-smelling, dark, or foamy fluid indicates overheating and internal wear.
Use a transmission-capable scanner to view live solenoid operation, line pressure readings, and input/output speed sensor data while the engine runs.
Clear P0748, perform a test drive that recreates the freeze frame conditions (same speed, load, temperature), and verify the code does not return.

Repair Options and Costs

Prices below reflect typical parts and labor at independent shops in USD. Actual quotes vary by vehicle and location.

Transmission fluid drain-and-fill or flush: $150–$350
Replacement of individual shift or pressure control solenoid: $300–$800
Valve body teardown, repair, or full replacement: $700–$1,500
Transmission rebuild or complete replacement: $2,500–$5,500

Start diagnosis with the least expensive possibilities — fluid condition, wiring, and connectors — before committing to solenoid or transmission work.

Driving Safety Assessment

P0748 carries a caution severity rating. If the transmission still shifts and the vehicle moves normally, short trips on surface streets are acceptable until you arrange repairs. Avoid sustained highway driving because slipping and harsh shifts accelerate internal wear and heat buildup. In limp-home mode, only two or three gears remain available — treat this as a signal to stop driving and seek service immediately. Every mile driven with a malfunctioning pressure control system can worsen internal damage and increase your final repair bill.