● Fix soon
Usually drivable for a short time, but check it soon. It can get worse.
Usually drivable for a short time, but check it soon. It can get worse.
The computer sees battery voltage below its normal range. The driver may notice dim lights, hard starting or several warning lights.
Guided check
- Is the voltage below about 13 V with the engine running?If yes: Test the alternator, belt and charging wires.
- Are the battery terminals or earth straps loose or corroded?If yes: Clean and tighten them, then test again.
- Does the battery fail a load test?If yes: Replace the battery and check the charging voltage again.
These checks are general and are still being reviewed by working mechanics.
Causes vary by car. Test before you order a part.
Likely causes, most common first
- Weak alternator
- Worn battery
- Loose or corroded battery terminals
- Slipping drive belt
Parts usually involved
- Alternator Find at suppliers
- Battery Find at suppliers
- Battery terminals Find at suppliers
- Drive belt Find at suppliers
Test before you replace
Measure battery voltage at rest and with the engine running under load, then test voltage drop on the main cables.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.