What P0561 means
The module measures its own supply voltage.
How the engine computer detects it
CARB allows other monitors to be suspended below 11 V, and above a maker's threshold only if the voltage itself is diagnosed – that is what these codes record. GM's engine modules and Ford's PCM set them without warning lamp. GM interprets P0561 as a difference between the module's two supply inputs: permanent battery and switched ignition supply may differ by at most 3 V, otherwise it sets after 50 of 63 samples. In the engine module that is type C without warning lamp, in GM's 9-speed transmission module type A with the lamp after one trip. Other makers use it for a fluctuating voltage.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Further voltage or communication codes
- Transmission warning or check engine light (GM transmission module)
- Sporadic dropouts of electrical functions
Common causes
- Fuse, relay or line of the ignition supply (voltage drop) Most likely
- Loose or corroded connector or ground at the module Possible
- Voltage regulator fluctuating Possible
- Battery terminal loose Possible
How to diagnose P0561
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: battery, alternator, module power supply, engine control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 5
- Vehicle speed, idle control and auxiliary inputs
- 61
- Specific fault
Questions drivers ask
Can I drive with code P0561?
Only for a short distance. When the charging system isn't working right, the car may run on battery power alone and can stall, sometimes taking power steering with it. Turn off accessories you don't need and head straight to a shop.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.