What are the common causes of P05BC?

A failed stop-start mode switch. An open in the switch wiring. A corroded switch connector. A failed body control module input. A blown fuse to the switch.

Watch the stop-start switch input on a scan tool. Test the switch wiring for an open. Inspect the switch connector for corrosion. Check the fuse that feeds the switch. Replace the switch if the input never changes. Clear the code and retest.

P05BC

Stop-Start Mode Switch Circuit/Open

System: Speed and idle control (P code)
Lamp: Check Engine Light
Category: Powertrain - Computer and Auxiliary Controls

What it means

P05BC means Stop-Start Mode Switch Circuit/Open.

Where it lives

For P05BC, the circuit described runs through the switch. The description of P05BC reports the switch as open.

Check these first

A failed stop-start mode switch
An open in the switch wiring
A corroded switch connector
A failed body control module input
A blown fuse to the switch

What to do next

Watch the stop-start switch input on a scan tool
Test the switch wiring for an open
Inspect the switch connector for corrosion
Check the fuse that feeds the switch
Replace the switch if the input never changes
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.