Code result
P0561
System Voltage Unstable
Moderate severity
What it means
The ECU monitors battery voltage and detects unstable behaviour - rapid fluctuations beyond what current load changes explain. Typical causes are a failing alternator, loose battery terminals, weak battery, or a heavy load (radiator fan, glow plugs, heated screen) drawing voltage down briefly.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Alternator regulator failing
highOne of the most commonly reported causes for this code — check this first.
Battery weak or terminals loose
mediumA plausible cause — test and verify before replacing parts.
Related help
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