P05BC
Stop Start Mode Switch Circuit/Open
Generic OBD-II
Real-world scan data
Seen in
22
scans in the past year
Found in
<0.1%
of scans
<0.1%
of scans that found faults
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check and repair any loose or damaged wiring connections related to the stop
- start mode switch circuit
- Inspect and replace the stop
- start mode switch if it is faulty or malfunctioning
- Verify and fix any issues with the stop
- start mode relay or fuse
- Reset the vehicle's electronic control module (ECM) to clear any error codes related to the stop
- start mode switch circuit.
Common causes
Most likely first
- Faulty stop start mode switch
- Damaged wiring or connectors in the stop start mode switch circuit
- Faulty stop start mode relay
- Low battery voltage or weak battery
- Faulty powertrain control module (PCM)
How to diagnose & fix
Work through it in order
- Engine may not start or may be difficult to start
- Engine may stall or shut off unexpectedly while driving
- Stop/start system may not function properly or may be disabled
- Check engine light may illuminate on the dashboard
- Vehicle may experience poor acceleration or reduced power
Read & clear P05BC yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.