AutoCodes – Subaru – P0748 Subaru

P0748 Subaru Code - Pressure Control Solenoid 'A' Electrical

Quick Answer

The Pressure Control (PC) Solenoid Valve an electronic pressure regulator that controls transmission line pressure based on current flow through its coil windings. Common causes include Dirty transmission fluid, Low transmission fluid level, Faulty line pressure solenoid valve 'A'. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0748 Subaru indicates Pressure Control Solenoid 'A' Electrical.
Common causes: Common causes include Dirty transmission fluid, Low transmission fluid level, Faulty line pressure solenoid valve 'A'.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 28,309

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 11, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0748 Subaru Description

The Pressure Control (PC) Solenoid Valve an electronic pressure regulator that controls transmission line pressure based on current flow through its coil windings. As current flow is increased, the magnetic field produced by the coil moves the solenoid’s plunger further away from the exhaust port. Opening the exhaust port decreases the output fluid pressure regulated by the PC solenoid valve, which ultimately decreases line pressure. The line pressure solenoid valve regulates the oil pump discharge pressure to suit the driving condition in response to a signal sent from the Transmission Control Module (TCM).

OBDII Code P0748 Subaru - Pressure Control Solenoid 'A' Electrical - AutoCodes.com — P0748 Subaru Code - Pressure Control Solenoid 'A' Electrical

What does this mean?

What are the Possible Causes of the DTC P0748 Subaru?

Dirty transmission fluid
Low transmission fluid level
Faulty line pressure solenoid valve 'A'
Line pressure solenoid valve 'A' harness is open or shorted
Line pressure solenoid valve 'A' circuit poor electrical connection

How to Fix the DTC P0748 Subaru?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

When a transmission solenoid is malfunctioned, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is dirty, it's recommended to change the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a mechanical transmission failure and that the transmission will need to be rebuilt or replaced.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0748 Subaru code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0748 Subaru Code

What does the OBDII code P0748 mean on a Subaru?

1. P0748 indicates an electrical issue with the Pressure Control Solenoid 'A' in the transmission, which regulates hydraulic pressure for proper shifting and operation. 2.

What are the common symptoms of code P0748 in a Subaru?

Symptoms include harsh or erratic shifting, transmission slipping, poor fuel efficiency, transmission overheating, and possible activation of limp mode. 3.

What causes the P0748 code to appear in a Subaru?

Common causes include a faulty pressure control solenoid, damaged wiring or connectors, a failing transmission control module (TCM), or low or contaminated transmission fluid. 4.

Can driving with the P0748 code damage my Subaru's transmission?

Yes, driving with this code can cause further damage to the transmission if the issue is not addressed promptly, especially if the transmission is overheating or slipping. 5.

How do I diagnose the P0748 code on my Subaru?

Start by checking the transmission fluid level and condition, inspecting the solenoid wiring and connectors for damage, and testing the pressure control solenoid and related circuits with a multimeter. 6.

Is replacing the pressure control solenoid necessary to fix P0748?

If the solenoid is confirmed to be faulty through testing, replacement is necessary. However, ensure other potential causes like wiring issues or a bad TCM are ruled out first. 7.

How much does it cost to fix the P0748 code in a Subaru?

Repair costs vary but typically range from $200 to $500 for solenoid replacement, with additional costs if wiring repairs or TCM replacement is required. 8.

Can low or dirty transmission fluid trigger the P0748 code?

Yes, low or contaminated transmission fluid can cause improper solenoid operation, leading to the P0748 code. Always check fluid levels and condition as part of the diagnosis. 9.

Will clearing the P0748 code fix the problem?

Clearing the code will temporarily remove it from the system, but the underlying issue must be repaired to prevent the code from returning. 10.

Do I need specialized tools to repair the P0748 code on my Subaru?

Basic tools like a multimeter and OBDII scanner can help with diagnosis, but repairing internal transmission issues may require professional tools and expertise.