U0299Lost Communication With DC/DC Converter Control Module B
- 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
- A second DC/DC converter, B, appears where a single support stage cannot serve every consumer or where two networks are fed separately. FCA documents the code: in PCM reflash bulletins 18-023-19 Rev. B and 18-020-21, covering 2019 Cherokee models with the 3.2 V6 and stop-start, U0299 is named as loss of contact to DC-DC converter 2. Next to it stand performance and over-temperature codes for converter 2 (P0EA5, P0EA6) and invalid data from converters A and B. Customers report a lit MIL and an engine that does not always restart after an auto stop; the remedy is new PCM software, not a new converter. With B missing, start-stop is typically withdrawn and voltage-sensitive electronics may reset during restarts.
- What you may notice
- Check engine lamp on
- Engine does not always restart after auto stop
- Start-stop function disabled
- Likely causes
- LikelyPowertrain control module software (FCA update)
- PossibleSupply, fuse or ground of converter B faulty
- PossibleBus wiring or connector to converter B damaged
- RareConverter B internally failed, e.g. after overheating
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.