U029F
Lost Communication With Evaporative Emission System Leak Detection Control Module
The vehicle bus reports loss of communication with the EVAP leak detection module. Tank-pressure / vacuum diagnostics for fuel-vapour leaks cannot be commanded.
- Check engine light: Yes
- Emissions related: Yes
- 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
- EVAP Leak Detection Module
- Vehicle Bus Wiring
U029F 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.