U04BAInvalid Data Received From Switch Input Module A
- Generic OBD-II code · Network
- How the car detects it
- A switch input module collects the positions of several buttons and reports them to other control units as network frames. U04BA means that frames from module A keep arriving, but the receiver, usually the body controller, rejects their content: a switch state outside the defined values, a wrong message counter, a failed checksum or an unexpected length. An Eaton patent describes such a module in which a controller polls each switch address and acts only on replies carrying a valid address and state. Which buttons belong to module A is up to the carmaker; no maker documents this code publicly. If module A falls silent, U01B7 is set instead. For the driver, the buttons handled by this module may do nothing or trigger the wrong function.
- What you may notice
- Buttons served by the module inoperative or acting intermittently
- Code stored in the body controller without a warning lamp
- Likely causes
- PossibleSwitch module or receiving controller with incompatible software or coding after repair
- PossibleSwitch input module A internally faulty (moisture, damaged switch contacts)
- RareCorroded connector or chafed data lead corrupting the frames
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.