What does code P1859 mean on Audi vehicles?
The transmission control module receives an error related to the brake switch signal from the engine control module.
OBD-II Code Audi
P1859 — Audi — Brake Switch Circuit Error Message from Engine Control Module
The transmission control module receives an error related to the brake switch signal from the engine control module.
Common symptoms
- Erratic shifting behavior
Possible causes
- Faulty brake light switch
- wiring issue
Initial recommendation
Inspect brake switch operation and related wiring.
Safety notice
This information is for guidance only. Brand-specific codes may vary by model, year, engine, transmission and vehicle configuration. It does not replace a physical inspection or diagnosis by a qualified mechanic. If the vehicle is unsafe to operate, avoid driving it and seek professional inspection.
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