AutoCodes – Generic – P1594

P1594 Code - Charging System Voltage Too High

Quick Answer

When the Powertrain Control Module (PCM) regulates the generator field and the there are no detected field problems but the voltage output does not decrease, the P594 code will set. Common causes include Faulty Ambient/Battery temperature sensor, Faulty Alternator, Alternator harness is open or shorted. 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 indicates Charging System Voltage Too High.
Common causes: Common causes include Faulty Ambient/Battery temperature sensor, Faulty Alternator, Alternator harness is open or shorted.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 13,524

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P1594 Description

When the Powertrain Control Module (PCM) regulates the generator field and the there are no detected field problems but the voltage output does not decrease, the P594 code will set.

OBDII Code P1594 - Charging System Voltage Too High - AutoCodes.com — P1594 Code - Charging System Voltage Too High

What does this mean?

What are the Possible Causes of the DTC P1594?

Faulty Ambient/Battery temperature sensor
Faulty Alternator
Alternator harness is open or shorted
Alternator electrical circuit poor electrical connection

How to Fix the DTC P1594?

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 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 code?

Need more information on how to fix the P1594 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1594 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1594 Chrysler — Charging System Voltage Too High
P1594 Dodge — Charging System Voltage Too High
P1594 Jeep — Charging System Voltage Too High
P1594 Subaru — Automatic Transmission Diagnosis Input Signal Circuit Malfunction

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 Code

1. What are the common symptoms of OBDII code P1594 (Charging System Voltage Too High)?

- Common symptoms include dashboard warning lights for the battery or charging system, flickering lights, and potential damage to electrical components.

2. What are the possible causes of OBDII code P1594?

- Potential causes may include a faulty voltage regulator, a malfunctioning alternator, damaged wiring in the charging system, or issues with the battery.

3. How can I diagnose the source of OBDII code P1594?

- Diagnosing the issue typically involves checking the alternator output voltage, inspecting the battery for signs of damage, and testing the voltage regulator for proper functioning.

4. Can driving with OBDII code P1594 cause further damage to the vehicle?

- Continuing to drive with this code present can potentially damage the battery, electrical components, and the charging system, leading to more costly repairs.

5. What are some possible repair tips for fixing OBDII code P1594?

- Repair tips may include replacing the alternator, voltage regulator, or damaged wiring, ensuring proper grounding of the charging system components, and checking the battery health.

6. Is it safe to continue driving with OBDII code P1594?

- It is not recommended to continue driving with this code present, as it could lead to further damage to the vehicle's electrical system and potentially leave you stranded due to a drained battery.

7. How much does it typically cost to repair OBDII code P1594?

- The cost of repair can vary depending on the specific cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

8. Can OBDII code P1594 be triggered by a loose or corroded battery connection?

- Yes, a loose or corroded battery connection can cause fluctuations in voltage, leading to the triggering of code P1594. It's recommended to check and clean battery connections as part of troubleshooting.

9. Are there any preventive maintenance steps to avoid OBDII code P1594?

- Regularly checking the condition of the battery, ensuring proper alternator and voltage regulator function, and maintaining a clean and secure electrical system can help prevent code P1594.

10. How long does it typically take to repair OBDII code P1594?

- The repair time can vary based on the specific cause and the extent of the issue, but it may take a few hours to a full day for diagnosis and repair by a qualified mechanic.