P0561 Code: System Voltage Unstable
🟠 Moderate severity · drivable
Drivable short-term, but unstable voltage can cause electrical faults, so diagnose the charging system soon.
What P0561 means
The engine computer is seeing system voltage that's fluctuating or unstable. Normal running voltage is a steady 13.5–14.5 volts; instability usually points to a charging-system problem.
Symptoms
- Check engine light is on
- Dim or flickering lights
- Electrical accessories acting up
- Possible stalling
Common causes
- most common: Failing alternator
- common: Weak battery
- common: Loose or corroded battery terminals
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Clean and tighten the battery terminals | Yes | $0–20 |
| Test the battery and replace it if weak | Yes | $100–250 |
| Test the alternator and replace it if failing | Mechanic | $200–500 |
Frequently asked questions
Can I drive with a P0561 code?
Short distances, yes, but the car could stall or fail to start. Get the charging system tested soon.
What is the most common cause of P0561?
A failing alternator or a weak battery.
How much does it cost to fix a P0561?
A battery is $100–$250; an alternator is $200–$500 installed.
Related codes
P0560
P0560 Code: System Voltage Malfunction
P0562P0562 Code: System Voltage Low
P0563P0563 Code: System Voltage High
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.