What the BlueDriver app can tell you about your alternator

The BlueDriver app reads diagnostic trouble codes from your vehicle's onboard computer through a small Bluetooth adapter that plugs into your OBD-II port. When your alternator is failing, your car's electrical system generates a code — usually P0562 (system voltage low) or P0563 (system voltage high) — that BlueDriver can display. The app shows you the exact code, what it means, and whether the problem points to the alternator or something else in the charging circuit.

BlueDriver does not directly measure alternator output the way a multimeter does. Instead, it reads what your vehicle's computer has already detected about electrical system problems. This is useful because it tells you whether your car has actually registered a fault, which is often the first sign something is wrong.

You will need a BlueDriver adapter (a small Bluetooth device that costs around $100) and the free BlueDriver app on your smartphone. The adapter connects to the OBD-II port under your dashboard, usually on the left side below the steering wheel.

Key Takeaways

  • BlueDriver reads diagnostic codes from your car's computer through a Bluetooth adapter, showing voltage problems that may indicate alternator failure.
  • Common alternator codes are P0562 (voltage too low) and P0563 (voltage too high), and BlueDriver displays these with plain-language explanations.
  • The app works only when your engine is running, and you should check codes both at idle and at 2,000 RPM to see how the system behaves under load.
  • A low-voltage code does not always mean the alternator is bad — it could be a weak battery, loose connections, or a faulty voltage regulator instead.
  • BlueDriver is a diagnostic tool that helps you understand what your car's computer detected, but a multimeter or professional test is needed to confirm alternator output.

Installing the BlueDriver adapter and app

read the BlueDriver app from the Apple App Store or Google Play Store and create a free account. The app itself is free; you pay only for the physical adapter if you do not already own one.

Locate your OBD-II port. In most vehicles made after 1996, it is a 16-pin connector under the dashboard on the driver's side, usually within arm's reach below the steering wheel. Some cars hide it behind a removable panel. Consult your owner's manual if you cannot find it quickly.

Plug the BlueDriver adapter into the OBD-II port. You will hear a click when it seats fully. The adapter will light up and begin broadcasting a Bluetooth signal. Open the BlueDriver app, go to the Bluetooth settings, and select the BlueDriver adapter from the list of available devices. Once paired, the app will show a green checkmark and display your vehicle's year, make, and model.

Reading voltage codes while the engine runs

Start your engine and let it idle for 30 seconds. Open the BlueDriver app and tap "Scan Vehicle" or the equivalent button in your version. The app will query your car's computer and display any stored or pending diagnostic codes.

Look for codes in the P05xx range, which relate to electrical system voltage. P0562 means the system voltage is lower than expected — a sign the alternator may not be charging properly. P0563 means voltage is higher than expected, which can indicate a faulty voltage regulator or alternator overcharging. If you see either code, note it and the number of times it has occurred.

Next, rev the engine to about 2,000 RPM and hold it steady for 10 seconds. Scan again. A healthy alternator should produce more voltage as engine speed increases. If the low-voltage code disappears at higher RPM, the alternator may be weak but still partially functional. If the code persists or worsens, the problem is more serious.

Understanding what the codes mean

A P0562 code (system voltage low) most often points to the alternator, but it can also come from a weak battery, corroded battery terminals, a loose serpentine belt, or a broken wire in the charging circuit. BlueDriver will display the code and a description, but it cannot tell you which component is actually at fault.

A P0563 code (system voltage high) usually indicates a faulty voltage regulator, which may be built into the alternator or mounted separately depending on your vehicle. Some vehicles also generate this code if the battery terminals are loose or corroded, preventing proper voltage feedback to the regulator.

If you see no codes at all but suspect alternator trouble — for example, your headlights are dimming or your battery warning light is on — the problem may not have triggered a code yet. In that case, BlueDriver alone cannot diagnose the issue, and you will need to use a multimeter to measure alternator output directly.

Clearing codes and rechecking after repair

If you have had work done on your charging system — a new alternator, battery, or serpentine belt — you can use BlueDriver to confirm the repair worked. Open the app, scan the vehicle, and verify that the voltage codes are gone.

BlueDriver allows you to clear codes from the app menu, though some vehicles require the battery to be disconnected for a few minutes to fully reset the system. After clearing, drive the vehicle normally for at least 50 miles. If the code returns, the underlying problem was not fixed. If it stays gone, the repair was successful.

Do not rely on code clearing alone as proof of a successful repair. A code can disappear temporarily even if the problem persists. Always rescan after a few days of normal driving to make sure the fault has not returned.

When BlueDriver is not enough

BlueDriver is a diagnostic reader, not a load tester. It tells you what your car's computer detected, but it does not measure the actual voltage or amperage your alternator is producing. To confirm an alternator is truly faulty, you need a multimeter or a dedicated alternator load tester.

A multimeter can measure alternator output at idle and under load. A healthy alternator typically produces 13.5 to 14.5 volts at idle with the engine running and the headlights off. If your multimeter shows lower voltage, or if voltage drops when you turn on the headlights and air conditioning, the alternator is likely weak.

If BlueDriver shows a voltage code but you want to be certain before paying for a repair, take your vehicle to a shop that offers free alternator testing. Many auto parts stores and dealerships will test your alternator and battery at no charge, giving you a definitive answer.

Frequently Asked Questions

Do I need to buy the BlueDriver adapter, or can I just use the app?

You need both. The app is free, but it only works when connected to the BlueDriver adapter via Bluetooth. The adapter is the physical device that plugs into your OBD-II port and communicates with your car's computer. Without it, the app cannot read any codes.

Will BlueDriver work on my car?

BlueDriver works on any vehicle with an OBD-II port, which includes all cars and light trucks sold in the United States since 1996. Check the BlueDriver website or app to confirm your specific year, make, and model before purchasing the adapter.

What if I see a voltage code but my car runs fine?

A stored code means your car's computer detected a problem at some point, even if the symptom is not obvious now. The alternator may be failing gradually. Monitor the code over the next few weeks using BlueDriver. If it returns repeatedly or if you notice dimming lights, slow cranking, or a battery warning light, have the charging system tested professionally.

Can BlueDriver tell me if my battery or serpentine belt is the problem instead of the alternator?

No. BlueDriver only reads codes; it cannot isolate which component in the charging circuit is faulty. A voltage code could come from the alternator, battery, regulator, wiring, or belt. You will need a multimeter test or a professional load test to narrow it down.

Should I clear the code myself after I see it?

You can, but it is better to leave it until after a repair. A cleared code makes it harder to track whether the problem is ongoing. If you do clear it, drive normally for 50 miles and rescan. If the code returns, the fault was not resolved.