P05BF: Stop-Start Mode Switch Circuit High
Standardized SAE J2012 code · P05xx — Vehicle speed, idle control and auxiliary inputs
What does P05BF mean?
The stop-start off switch lets the driver disable automatic engine stop for the current drive. It is read directly or via another module over CAN – on Stellantis' 2025 Ram 1500 it sits in the electronic shifter module. CARB names a stop-start diagnosis as its example of an emission-neutral diagnosis, so no warning lamp is required; stop-start is usually just disabled. P05BF means the switch circuit voltage is too high – a short to positive or, with a pull-up, a missing switch ground. No manufacturer document available to us uses this code.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Stop-start cannot be switched off or stays disabled
- Switch indicator not working
- Usually no check engine light
Common causes
- High Signal line shorted to positive
- Medium Switch ground open (signal pulled up)
- Medium Switch faulty
- Low Module input
Likelihood is a general estimate across vehicles; your make and model may differ.
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