OBD-II Code B1325 — What It Means & How to Fix It

What Does This Error Mean?

B1325 means a control module detected that the power supply voltage was out of range. This code appears when the voltage reaching a body or safety module is too low or too high. Low voltage is most commonly caused by a weak battery, a failing alternator, or a bad ground connection. Multiple electrical gremlins showing up at the same time — combined with B1325 — almost always point to a battery or charging system problem.

Affected Models

Ford F-150, Ranger, and Explorer
Lincoln Continental and Town Car
GM trucks and SUVs
Most 1996+ vehicles with body control modules

Common Causes

A weak or failing battery that cannot hold adequate voltage
A failing alternator that is not maintaining proper charging voltage (should be 13.5–14.7V while running)
A poor ground connection between the battery and the vehicle's body or frame
Corroded battery terminals creating resistance in the power supply circuit
A voltage regulator failure inside the alternator

How to Fix It

Take your vehicle to any auto parts store (AutoZone, O'Reilly, Advance Auto Parts) for a free battery and alternator test. These tests take about 5 minutes and will immediately tell you if either component is failing.

This is your best first step. Battery and charging problems are responsible for a large percentage of B1325 codes, and the test is completely free.
While the hood is open, inspect the battery terminals for corrosion — white, blue, or greenish buildup around the terminal posts. Corroded terminals add resistance that drops voltage reaching the modules.

Clean corroded terminals with a wire brush or a baking soda and water mixture. Rinse with water and dry thoroughly. This is free to do yourself.
Check the negative battery cable and any body ground straps. Trace the ground cable from the battery to where it bolts to the body or frame. Loosen the bolt, clean both surfaces, and retighten.

Bad grounds are one of the most underdiagnosed causes of electrical faults in vehicles. A loose or corroded ground can cause dozens of seemingly unrelated codes.
If the battery and alternator both test good, scan the vehicle with a professional-grade tool to identify which specific module logged B1325. Different modules can log this code, so identifying the source narrows down the wiring to inspect.

Voltage specifications vary by manufacturer — a professional technician knows the exact acceptable voltage range for your vehicle's modules.
Replace the battery or alternator if testing confirms they are failing. After replacement, clear the B1325 code and allow the vehicle to run through several drive cycles to confirm it does not return.

If B1325 returns after battery and alternator replacement, a wiring fault in the power supply circuit to the affected module is the next area to investigate.

When to Call a Professional

Battery and alternator testing is free at most auto parts stores. If the alternator needs replacement, expect $250–$500 installed. If only the battery is the issue, a new battery runs $100–$200. Ground cable replacement is typically $50–$150 in labor. A technician can use a multimeter to confirm whether the problem is the battery, alternator, or ground.

Frequently Asked Questions

Can a bad battery really cause all these electrical codes?

Absolutely. A battery that is losing capacity will show adequate voltage at rest but drops sharply under load. This voltage drop confuses control modules and causes them to log faults. A single failing battery can generate 5 to 10 different error codes across multiple systems at the same time. Always test the battery first before diagnosing individual modules.

What voltage should my alternator produce?

A healthy alternator should produce between 13.5 and 14.7 volts with the engine running. Below 13 volts means the alternator is not charging the battery properly. Above 15 volts means the voltage regulator may be failing and sending too much voltage to the electrical system. Both extremes can trigger B1325.

How long can I drive with B1325?

If the battery or alternator is failing, you may only have a short time before the vehicle stalls or will not restart. Do not ignore this code. Get the battery and charging system tested as soon as possible — ideally the same day.