Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. P2504 OBD-II Trouble Code: Charging System Voltage High

P2504 OBD-II Trouble Code: Charging System Voltage High

check engine light

P2504 code definition

The P2504 OBD-II fault code simply means that an irregularity was detected in the charging system circuit - specifically that the voltage was high. This high voltage reading may have originated from the battery, charging system, or starter.

What the P2504 code means

The P2504 trouble code means that a higher than normal voltage within the charging system was detected. The code alone, however, does not indicate whether this high reading is an intermittent or ongoing issue.

What causes the P2504 code?

Most commonly caused by a faulty alternator or other charging system issue, the PCM detects a voltage higher than the accepted parameters, registers the P2504 code, and then illuminates the Check Engine Light on the vehicle’s dashboard.

What are the symptoms of the P2504 code?

Aside from the illumination of the Check Engine Light, a vehicle registering the P2504 code may also display one or more of the following symptoms:

  • Engine stalling when on idle
  • Decrease in fuel efficiency
  • Improper shifting in a vehicle with an automatic transmission
  • Red battery light may come on the dashboard

How does a mechanic diagnose the P2504 code?

Using a specialized scan tool with a greater sensitivity and scope of application than those found in auto parts stores, a mechanic can verify the existence of the P2504 code. Using the information collected and provided by that scan tool, the mechanic can then use professional reference materials to interpret that data and determine a probable cause for the trouble code registering.

The technician then performs a hands-on inspection of the affected system and most likely culprits, replacing any worn components or making other needed repairs. Afterwards, the mechanic may test drive the vehicle and use the scan tool again to verify that the issue has been resolved.

Common mistakes when diagnosing the P2504 code

The most frequent mistakes a mechanic may make within a P2504 trouble code diagnosis are:

  • Not verifying the existence of the P2504 code

  • Failing to test the alternator and unnecessarily replacing the battery or starter

  • Failing to thoroughly inspect the alternator, battery and related charging system components

  • Forgetting to clear the P2504 OBD-II fault code after making needed repairs

How serious is the P2504 code?

Since the P2504 code registers due to voltage abnormalities in the alternator, battery, or charging system, the problem can worsen over time, ultimately preventing a vehicle from starting or staying running. If the issue is left neglected, such voltage spikes may affect other components or systems, resulting in more costly repairs down the road.

What repairs can fix the P2504 code?

After the validation of the P2504 code by a qualified mechanic in possession of a specialized scan tool, the following repair(s) may be required:

  • Reinstalling primary or secondary grounds
  • Repairing wiring or battery cables
  • Replacing corroded battery terminal ends
  • Replacing an alternator, battery, or starter
  • Replacing a defective voltage regulator
  • Replacing a faulty PCM in rare cases

Additional comments for consideration regarding the P2504 code

Since there are multiple potential causes of the P2504 code registering, it can take up to several hours for a qualified mechanic to accurately diagnose the cause of the fault code. Multiple scans and other tests may be in order even after repairs have been made to verify the issue has been satisfactorily resolved.

Need help with a P2504 code?

Let YourMechanic connect you with an experienced and qualified mechanic to diagnose and repair the cause of the P2504 code in your vehicle. If needed, that technician can even come to you at your home or office for your convenience and safety. Receive a quote, book an appointment with a mechanic online or talk with a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
The Traveler’s Guide to Driving in Malaysia
CraigBurrows / Shutterstock.com Malaysia is a popular destination for many tourists today. The country has amazing sights and attractions that you will want to explore....
How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...


Related questions

Q: How to repair the P2238 trouble code in my car

Hi there. This P2238 code is set when the engine computer detects a short circuit on the heater for the 02 or AF sensor.The short is generally in the sensor itself and replacement corrects the condition. However, there could be...

Q: Car starting hard

The most common faults that cause your hard start can be a EVAP Purge Solenoid that is on the intake manifold. It's relatively easy to replace and only around $25. Or, it can be a fuel pump pressure issue that...

Q: Check Engine Light is on, trouble codes P0001 and P0006 are showing.

The fuel shut off valve is a solenoid that is controlled primarily by the shut off relay. The message you are receiving is telling you the circuit has low voltage. This means the solenoid is not energizing the way it...