AutoCodes – Subaru – P1594 Subaru

P1594 Subaru Code - Automatic Transmission Diagnosis Input Signal Circuit Malfunction

Quick Answer

P1594 Subaru indicates Automatic Transmission Diagnosis Input Signal Circuit Malfunction. Common causes include Faulty Transmission Control Module (TCM), TCM harness is open or shorted, TCM circuit poor electrical connection. 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: P1594 Subaru indicates Automatic Transmission Diagnosis Input Signal Circuit Malfunction.
Common causes: Common causes include Faulty Transmission Control Module (TCM), TCM harness is open or shorted, TCM circuit poor electrical connection.
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 5,963

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 May 20, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1594 Subaru Description

OBDII Code P1594 Subaru - Automatic Transmission Diagnosis Input Signal Circuit Malfunction - AutoCodes.com — P1594 Subaru Code - Automatic Transmission Diagnosis Input Signal Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P1594 Subaru?

Faulty Transmission Control Module (TCM)
TCM harness is open or shorted
TCM circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P1594 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1594 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.

Need more information about the P1594 Subaru code?

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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 P1594 Subaru Code

1. What are the common symptoms of OBDII code P1594 in a Subaru related to the Automatic Transmission Diagnosis Input Signal Circuit Malfunction?

Common symptoms include issues with shifting gears, hesitation or slipping during acceleration, and the transmission sticking in one gear.

2. What can cause the OBDII code P1594 to trigger in a Subaru?

The code P1594 in a Subaru is often triggered by a faulty transmission input signal circuit, damaged wiring, or a malfunctioning transmission control module.

3. How can I diagnose the OBDII code P1594 in my Subaru?

Diagnosing the code P1594 involves using an OBDII scanner to retrieve the code and then inspecting the transmission input signal circuit, checking for any damaged wiring or loose connections.

4. What repairs are typically needed to fix the OBDII code P1594 in a Subaru?

Repairs for the code P1594 may include repairing or replacing damaged wiring, fixing any loose connections, or replacing the transmission control module if it is faulty.

5. Can I continue driving my Subaru with the OBDII code P1594?

It is not recommended to continue driving your Subaru with the code P1594 present, as it can lead to further damage to the transmission and potentially unsafe driving conditions.

6. Are there any DIY tips for addressing the OBDII code P1594 in a Subaru?

While basic inspections like checking for loose connections can be done DIY, it is recommended to consult a professional mechanic for a thorough diagnosis and repair of the code P1594 in a Subaru.

7. How much does it typically cost to repair the OBDII code P1594 in a Subaru?

The cost of repairing the code P1594 in a Subaru can vary depending on the extent of the damage and the specific repairs needed. It is advisable to get a quote from a trusted mechanic.

8. What are the long-term effects of ignoring the OBDII code P1594 in a Subaru?

Ignoring the code P1594 can lead to further transmission damage, potential safety hazards on the road, and eventually more costly repairs down the line.

9. Can weather conditions or driving habits contribute to the OBDII code P1594 in a Subaru?

Extreme weather conditions or rough driving habits can potentially exacerbate existing issues related to the code P1594, so it's important to drive carefully and maintain your vehicle properly.

10. Is the OBDII code P1594 specific to Subaru vehicles, or can it occur in other car makes and models?

While the specific code P1594 may vary across different car makes and models, similar transmission input signal circuit malfunctions can occur in other vehicles as well, requiring similar diagnostic and repair procedures.