P0560
System Voltage
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OBD2 code P0560 — System Voltage — is stored by the powertrain control module (PCM) when it detects that the vehicle's electrical system voltage has fallen outside the normal operating range, typically below approximately 10 volts or above 16 volts. Because virtually every electronic system in a modern vehicle depends on stable voltage, the PCM monitors this parameter continuously and flags P0560 as a warning that the charging system or battery may no longer be functioning correctly.
The most frequent culprits behind P0560 are a weak or dying battery, a failing alternator, or corroded battery cable connections. Diagnosing the code yourself begins with a simple battery load test and a charging system voltage check using an inexpensive multimeter or automotive scan tool. A healthy charging system should read between 13.5 and 14.5 volts at the battery with the engine running. Readings outside this range point toward the alternator or voltage regulator. If charging voltage is normal, inspect battery terminals for corrosion, check cable integrity, and consider performing a parasitic draw test to identify any abnormal key-off current consumption.
While P0560 alone may not prevent you from driving short distances, it should not be ignored. Persistent low voltage can cause the PCM and other control modules to behave erratically, leading to seemingly unrelated driveability problems, harsh transmission shifts, and a cascade of secondary fault codes. Addressing the root cause promptly protects expensive electronics and prevents an unexpected no-start situation. Most repairs — battery replacement, terminal cleaning, or alternator swap — are well within the capabilities of a home mechanic with basic tools.
Severity
Symptoms
- •Battery warning light illuminated on dashboard
- •Erratic or flickering instrument cluster readings
- •Intermittent electrical accessory malfunctions (radio, power windows, lights)
- •Engine stalling or difficulty starting
- •Transmission shifting abnormally or erratically
- •Multiple unrelated DTCs stored simultaneously
Likely Causes
An aging battery that can no longer hold an adequate charge is the most common cause of P0560. As battery capacity degrades, voltage drops below the PCM's acceptable threshold, especially under load.
The alternator is responsible for maintaining system voltage while the engine runs. A worn alternator or internal regulator failure will cause chronic low or fluctuating voltage that triggers this code.
High resistance from corroded terminals or loose cable connections creates voltage drop under load. Even a clean-looking terminal can have internal corrosion causing significant resistance.
An abnormal current draw when the vehicle is off can deplete the battery overnight or over several days, resulting in low voltage conditions that set this code on startup.
Damaged wiring, a poor ground connection, or a failing PCM power relay can cause the module to sense incorrect system voltage. This is less common but should be checked after ruling out charging system issues.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the battery if load testing shows it is below specification
- Clean and tighten battery terminals and cable ends
- Test and replace the alternator if output voltage is outside the 13.5–14.5V range
- Perform a parasitic draw test and repair the circuit responsible for excessive key-off current
- Inspect and repair any damaged wiring or ground straps in the charging circuit