P0560: System Voltage
P0560 means a control module has detected that the vehicle's electrical system voltage is outside the range it expects. It is usually caused by a weak battery or a charging problem, and it can be minor, but in some vehicles it puts the transmission into limp mode.
You can drive, but get it checked soon
The car may drive normally, but a failing battery or alternator can leave you stranded, and on some vehicles the transmission drops into limp mode. Have the charging system tested soon, and stop driving if the charge warning stays on or the car starts to run poorly.
What it means
A control module measures its own supply voltage, the voltage the battery and alternator deliver to it. P0560 is the general system voltage code, with no split between low and high voltage, and manufacturers use it differently. One Saab transmission module sets it below 9 V or above 18 V for 1 second and then goes into limp mode, a reduced-power mode that protects the transmission. A Saab diesel module sets it only above 17 V, for example from a 24 V charger or a jump start. On the GM-built 9-4X it works as a low-voltage code. GM and Ford engine modules use P0562 (low) and P0563 (high) instead. The code does not turn on the check engine light and is not an emissions code.
Likely causes
- Battery weak or faultyVery likely
A battery that cannot hold voltage lets system voltage sag, especially during starting or when electrical loads are on.
- Alternator or regulator (under- or overcharging)Very likely
The alternator and its regulator control charging voltage, and a fault can leave it too low or push it too high.
- Jump start or charger at 24 VPossible
Connecting a 24 V source can push system voltage above the limit and set the code, as on the Saab diesel.
- Corroded or loose battery terminals or ground strapPossible
Poor connections add resistance, so the modules see a lower or unstable voltage even when the battery is healthy.
What you may notice
- Charge warning light on the dashboard
- Transmission limp mode (Saab)
- Codes stored in several modules at once
- Starting problems
What to check, cheapest first
- 1Look at the battery terminals and the ground strap for corrosion or looseness, and tighten or clean them. · you can do it
- 2Check whether the charge warning light is on and whether anyone recently jump started the car or used a charger. · you can do it
- 3Measure battery voltage with the engine off and while running, using a multimeter or a free test at a parts store. · you can do it
- 4Have the battery load tested to see whether it can hold voltage under demand. · mechanic
- 5Test the alternator output and regulator for undercharging or overcharging. · mechanic
- 6Read all modules for stored codes, fix the voltage problem, then clear the codes and confirm they do not return. · mechanic
Related codes
Frequently asked questions
Can I drive with a P0560 code?+
Briefly, with caution. If the charge light is on or the car enters limp mode, the battery or alternator may fail soon, so get it tested before long trips.
Can a bad battery cause P0560?+
Yes. A weak or faulty battery is one of the two most likely causes, along with the alternator or its regulator.
Will P0560 fail an emissions test?+
The code is not emissions related and does not turn on the check engine light. The underlying voltage problem can still cause other faults, so fix it first.
Written with the help of AI from the public OBDex definition (CC0). Each make may use the code differently. Updated: 2026-11-10