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P2503 OBD-II Trouble Code: Charging System Voltage Low

Check Engine Light

P2503 code definition

Charging System Voltage Low

What the P2503 code means

This diagnostic trouble code (DTC) indicates that the powertrain control module (PCM) has detected that the charging system is no longer producing the correct voltage to sufficiently charge the battery.

What are the causes of the P2503 code?

  • A faulty alternator
  • A faulty battery
  • Damaged battery terminal ends or battery cables
  • Corrosion on the battery connections or chassis grounds
  • Faulty voltage regulator (if not part of the alternator)
  • A faulty powertrain control module
  • A parasitic draw on the battery

What are the symptoms of the P2503 code?

Symptoms of this trouble code that the driver may experience would include:

How does a mechanic diagnose the P2503 code?

  1. A mechanic may begin diagnosing this trouble code by locating the vehicle’s battery.

  2. Then, the mechanic would use a digital multimeter to measure the voltage the battery is receiving with the engine running. Anything below fourteen volts is considered a low charging voltage. This test will likely fail.

  3. The mechanic would then check the battery using a high tech battery tester to determine if the battery is good enough to hold a charge. During this test, the mechanic would ensure that the battery and cables are corrosion free.

  4. The powertrain control module would be tested if no issues were found in the previous tests.

After all diagnostic tests are complete, the mechanic would relay his/her findings over to the customer to make a repair decision.

Common mistakes when diagnosing the P2503 code

A common mistake when diagnosing this trouble code would be to replace the battery since it is named in the trouble code definition. Although a bad battery is a possible cause, this trouble code is referring to the lack of charging to the battery, which sounds more like another part has gone bad that relates to the battery. It is important to consider all angles when diagnosing Check Engine Lights.

How serious is the P2503 code?

This code is very serious as it can prevent the vehicle from starting or even worse, cause it to die while driving down the road. This code could cause a severe inconvenience for the driver. Codes such as this will often end up causing tow bills when the car dies as a result of it.

What repairs can fix the P2503 code?

  • Replacing the alternator
  • Replacing the battery
  • Removing corrosion from the battery connections
  • Replacing the battery cables or terminal ends
  • Replacing the voltage regulator (if separate from the alternator)
  • Repairing or replacing wiring or connectors that are associated with this system
  • Replacing the powertrain control module

Additional comments regarding the P2503 code

Corrosion is the number one enemy for a battery. Always check your battery for corrosion every time the hood is opened to help prevent trouble codes such as this one. Some manufacturers make a product that can be sprayed out of a rattle can onto the battery terminal ends to help prevent battery corrosion. It would also help to spray this chemical on the connections of the alternator as well.

Need help with a P2503 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to 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

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