Drive with caution; a failing alternator can strand you. P0560 means the ECM saw its supply voltage outside the normal range. It usually points to a weak battery, a charging-system problem, or a bad ground or connection — and the ECM may have lost its stored memory in the process.
What P0560 means
The ECM needs a steady supply voltage to operate, plus constant battery power even with the key off so it can retain fuel trims, freeze-frame data, and trouble-code history. When that voltage drops too low or becomes unstable, the ECM flags P0560. The root cause is almost always in the battery, charging system, or wiring — not the ECM itself. A telltale sign is other stored codes or readiness monitors resetting because the keep-alive memory was cleared.
Symptoms
- Check engine light on
- Battery or charging warning may also appear
- Hard starting or slow cranking
- Erratic electrical behavior
- Readiness monitors or fuel trims resetting
- Stalling in severe cases
Common causes
- Weak or failing battery
- Failing alternator or voltage regulator
- Corroded or loose battery terminals and ground connections
- Blown fuse feeding the ECM keep-alive memory
- Damaged wiring or a poor main ground strap
- Excessive parasitic draw discharging the battery
Severity & driving advice
Severity: Moderate — If the charging system is failing, the vehicle could lose power and strand you, so verify the battery and alternator before relying on the car.
Can I drive? Drive with caution; a failing alternator can strand you.
Diagnostic approach
- Load-test the battery — A battery that fails a load test or has low resting voltage is the most common cause and should be corrected first.
- Measure charging voltage — With the engine running, system voltage should sit around 13.5–14.5V. Low or fluctuating output points to the alternator or regulator.
- Inspect terminals and grounds — Clean and tighten the battery terminals and main engine/body grounds; corrosion here causes voltage drops that set the code.
- Verify constant power to the ECM — Confirm the keep-alive (always-hot) fuse and B+ feed to the ECM are intact.
- Check wiring for voltage drop — Perform voltage-drop tests on the power and ground paths to the ECM under load.
- Test for parasitic draw — A drain that flattens the battery overnight can trigger recurring P0560 at the next start.
Make & model notes
Toyota / general: The battery feeds the ECM even with the ignition off to preserve trouble codes, freeze-frame and fuel-trim data. If voltage falls below the minimum the memory clears and the code sets at the next start, so recurring P0560 usually means a weak battery or a poor always-hot connection.
General: After replacing a battery, clean and torque the terminals — a loose or corroded connection alone can set P0560 even with a good battery.
FAQ
Can I drive with P0560?
Cautiously. If the alternator is failing you risk stalling and being stranded, so verify the charging system first.
Is it the battery or the alternator?
Test both: load-test the battery and measure charging voltage (about 13.5–14.5V running). A weak battery or low charging output is the usual cause.
Will a new battery fix P0560?
Often, if the old battery was weak or the terminals were corroded. Also confirm the alternator and grounds are good so it doesn't return.
Why did my other codes disappear?
A voltage drop can clear the ECM's keep-alive memory, erasing stored codes, fuel trims, and readiness monitors — which is itself a clue that voltage dipped too low.