OBD-II trouble code
P0562: System Voltage Low
The PCM is seeing battery voltage below the threshold needed for normal operation — usually a failing alternator, an aging battery, or a poor connection on the main charging circuit.
Quick facts
- System
- Powertrain
- Category
- Charging / Electrical
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $800
- DIY difficulty
- Intermediate DIY
What does P0562 mean?
P0562 sets when the powertrain control module monitors system voltage and sees it stay below a calibrated minimum — typically around 10.5 to 11.5 volts — for a sustained period with the engine running. A healthy charging system should hold somewhere between 13.8 and 14.7 volts with the engine at idle and accessories on. When the actual value falls below the floor, the PCM logs P0562 because the rest of the engine control system, including injectors, ignition coils, and the fuel pump, can't function correctly at low voltage.
The leading cause is the alternator itself — worn brushes, a failing rectifier, or a failed internal voltage regulator are all classic failure modes that appear after 80,000-150,000 miles. A weak battery comes next: an aging battery with high internal resistance can't accept the alternator's output cleanly, and the system voltage sags even when the alternator is healthy. Poor connections at the battery terminals, the alternator output stud, or the main ground strap to the engine block round out the common cases. A loose or worn serpentine belt can also let the alternator slip enough to under-produce, particularly at idle with heavy loads.
P0562 usually shows up with other electrical complaints — dim headlights at idle, slow power windows, a battery warning lamp on the dash, or an engine that wants to stall when AC and headlights are both on. Severe cases will leave you stranded with a dead battery, since the alternator isn't replacing the charge the starter pulled out. The good news is that this code is one of the easier ones to diagnose — a 30-second voltmeter check usually points straight at the cause.
Common causes
- Failing alternator (worn brushes, bad rectifier, or failed voltage regulator)
- Aging or sulfated battery with high internal resistance
- Loose, corroded, or undersized battery cable connections
- Failed or corroded engine-to-chassis ground strap
- Loose, glazed, or worn serpentine belt slipping at idle
- Damaged main output wire from alternator to battery
- Excessive parasitic draw discharging the battery overnight
- Failed alternator decoupler pulley on engines that use one
- Aftermarket audio or accessory installation drawing more than the alternator can supply
Symptoms
- Check engine light on with P0562 stored
- Battery warning lamp on the instrument cluster
- Headlights and interior lights dim noticeably at idle
- Slow power windows and sluggish wiper operation
- Engine struggles or wants to stall with AC and headlights on
- Battery dies repeatedly or won't hold a charge overnight
- Slow cranking on the next start
Diagnostic steps
- 1.Measure battery voltage with the engine off — a healthy battery reads 12.4-12.7 volts after sitting overnight.
- 2.Start the engine and measure again at the battery terminals — a working charging system reads 13.8-14.7 volts at idle.
- 3.Turn on headlights, blower fan, and rear defroster. Voltage should hold above 13.5. A drop into the 12s indicates the alternator is under-producing.
- 4.Inspect battery terminals for corrosion or looseness. Even a thin coating of green crust can drop voltage significantly.
- 5.Visually check the serpentine belt for glazing, cracking, or slack. Push on it with the engine running and listen for chirp or squeal.
- 6.If voltage tests confirm under-charging, perform a full charging system load test at a parts store or shop before replacing parts.
Repair cost
$100 – $800
Battery replacement runs $150-$300 installed for a standard flooded battery and $250-$450 for AGM. Alternator replacement is $400-$800 depending on access. Cable or ground strap repair is the cheapest fix at $80-$200. Most parts stores will load-test the battery and alternator for free, which is worth doing before any parts decisions.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with alternator replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.