U029FLost Communication With Evaporative Emission System Leak Detection Control Module
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Some evaporative systems run the leak test through a separate module that holds its own valve, pressure switch or sensor and reports results to the engine controller. U029F is stored when those reports no longer arrive. Kia documents it for the Niro hybrid of 2017 to 2019: bulletin PS593 describes a MIL with U029F00 and, on cars built before October 2018, asks for a resistance check of the yellow signal wire between pin 12 of joint connector EF11 and pin 2 of the natural vacuum leak detection plug F56, since damaged insulation or corroded strands near F56 cause an open circuit. Ford's 2014 code list marks the code as a MIL code. CARB 1968.2 requires gasoline vehicles to find leaks as small as 0.020 inch, so the EVAP monitor cannot run. Driving is not affected.
- What you may notice
- MIL on
- EVAP readiness not set
- No noticeable change in driving
- Likely causes
- LikelyDamaged insulation or corroded strands in the module signal wire
- PossibleCorrosion or water at the leak detection module connector
- PossibleSupply or ground of the leak detection module interrupted
- RareLeak detection module internally failed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.