U0253
Lost Communication With Accessory Protocol Interface Module
The vehicle bus reports loss of communication with the accessory protocol interface module (APIM). Infotainment, voice control and connected services that route through APIM stop responding.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
Ordered by how often each turns out to be the cause.
- Bus wiring open or shortedCommon
- Module without power or groundPossible
- Module failedPossible
Parts involved
- Accessory Protocol Interface Module
- Vehicle Bus Wiring
U0253 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.