P2504 OBD-II Trouble Code: Charging System Voltage High

Our certified mechanics come to you · Get a fair and transparent estimate upfront

EXCELLENT RATING ON

Cost of diagnosing the P2504 code

P2504 is a diagnostic trouble code (DTC) for "Charging System Voltage High". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $154.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $50.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate* Credit towards follow-up repair Earliest Availability
Ford $154.99 $50.0
Toyota $154.99 $50.0
BMW $164.99 $50.0

*Estimates may vary by market

SCHEDULE P2504 DIAGNOSTIC Get a fair and transparent estimate upfront

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.

Check Engine Light
trouble codes
P2504

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P2504 code.

SCHEDULE P2504 DIAGNOSTIC
Get a $50 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(8600)

Rating Summary
8017
273
65
46
199
8017
273
65
46
199
 at YourMechanic

Brandon

9 years of experience
133 reviews
Brandon
9 years of experience
Ford Escort L4-2.0L - Check Engine Light is on - Nashville, Tennessee
Brandon showed up ahead of schedule, was very personable and diagnosed my problems. He also scheduled my next appointments which will be with him.
 at YourMechanic

William

23 years of experience
33 reviews
William
23 years of experience
Lexus IS250 V6-2.5L - Check Engine Light is on - Mableton, Georgia
Arrived early which was great. William was courteous, and attentive to the issue. Even though it took several attempts I'm so happy he was determined to fix it and he did!
 at YourMechanic

Dan

40 years of experience
1080 reviews
Dan
40 years of experience
Plymouth Grand Voyager - Check Engine Light is on - Lawrenceville, Georgia
Mr. Dan Barber was quite patient, courteous and quite knowledgeable. From my observation, Mr. Barber appears to be quite professional.
 at YourMechanic

Christopher

9 years of experience
120 reviews
Christopher
9 years of experience
Ford Fiesta L4-1.6L - Check Engine Light is on - Smyrna, Georgia
Chris communicated with us each step of the way up until his arrival. He listened well, was knowledgeable, and was prepared. He took the time to diagnose the problem, explained the what, why and how and provided a solution. I would definitely recommend him and will use him again.


More related articles

P2564 OBD-II Trouble Code: Turbocharger Boost Control Position Sensor Circuit Low
P2564 code means that the boost levels are not within the normal parameters due to a dirty air filter, manifold issues, or failed intercooler.
P0658 OBD-II Trouble Code: Actuator Supply Voltage “A” Circuit Low
P0658 means that there is a fault in the actuator supply voltage due to Shorted or open wires or damaged connectors in the PCM, or a control module.
B1212 OBD-II Trouble Code: EIC Switch-2 Assembly Circuit Short To Ground
B1212 means a short circuit has been detected in the dashboard EIC, possibly due to wiring issues or a blown fuse.

Related questions

What Do Transmission Error Codes Tell You?
Using transmission error codes (https://www.yourmechanic.com/article/the-most-common-error-codes-for-transmission-problems) is a necessary procedure for a transmission technician since automatic transmissions have been computer controlled for over 20 years. The transmissions currently in use are very different to diagnose and repair than transmissions from decades...
New battery & fuel pump. Hours later car starts and shuts down 3X in a row. Finally it starts, 48 hours later, won't start at all
Checking all the fuses was a good move. I would also want to put a scan tool on it and check for diagnostic trouble codes (https://www.yourmechanic.com/article/how-to-read-and-understand-check-engine-light-codes-by-jason-unrau) (DTCs) as well as seeing the data that the computer is seeing. A fuel...
The check engine light is on and my car sounds loud when it I crank it up. What could be the cause?The exhaust got fix but still l
Hello, thank you for writing in. With the check engine light on, we need to start by scanning the vehicle for diagnostic codes to find out why that light is on. We can use the codes to help point us...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com