OBD-II Code
P0561
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$80–$680
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P0561 indicates the PCM saw system voltage fluctuating outside the normal narrow band during steady-state operation, usually swinging more than 1.0 to 1.5 volts within a few seconds.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0561 indicates the PCM saw system voltage fluctuating outside the normal narrow band during steady-state operation, usually swinging more than 1.0 t…
P0561 indicates the PCM saw system voltage fluctuating outside the normal narrow band during steady-state operation, usually swinging more than 1.0 to 1.5 volts within a few seconds.
This points to charging system instability
a failing alternator with worn brushes, an open diode in the rectifier bridge, a slipping serpentine belt under electrical load, or a loose battery cable that breaks contact under vibration. Cheapest-first: with engine running at 1500 rpm and headlights on, voltage at the battery should hold steady at 13.8 to 14.6V. Watch the scan tool's battery voltage PID for a full minute; healthy systems vary less than 0.2V. If you see voltage hunting 13.0 to 15.0V or AC ripple on the DC bus above 0.5V AC (set the multimeter to AC volts at the battery), the alternator's rectifier has a bad diode. Always verify both battery cables are torqued and corrosion-free first; a loose negative cable produces identical symptoms. Expensive misdiagnosis: replacing the alternator three times when the actual fault is a worn drive belt slipping under A/C compressor load.
Vehicle-specific patterns2005-2013 Chevrolet Impala and Malibu with the 3.5L/3.6L LFX develop alternator decoupler pulley failure that lets the alternator overspeed-undervolt…
- 2005-2013Chevrolet Impala and Malibu with the 3.5L/3.6L LFX develop alternator decoupler pulley failure that lets the alternator overspeed-undervolt cyclically.
- 2009-2014Ford F-150 5.0L and 3.5L EcoBoost have a TSB for the alternator's internal voltage regulator hunting between 12.8V and 15.2V.
- 2007-2013GMC Sierra and Chevrolet Silverado lose battery cable continuity at the molded connector to the underhood fuse block; voltage drops on hard left turns.
- 2003-2009Toyota 4Runner V8 develops a slipping serpentine belt that glazes over and squeals under high A/C compressor load, dropping voltage 1.0V at each load cycle.
Estimated repair$80 to $680.
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