U04B6Invalid Data Received From Catalyst Heater 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
- An electrically heated catalyst brings the converter to working temperature right after a cold start. Vitesco's EMICAT heater runs at 12, 24 or 48 V and can draw up to 300 A, has been ordered for 48-volt mild hybrid diesel vans with production planned from 2022, and in high-voltage hybrids is fed by a dedicated DC/DC converter. The electronics that switch this power report heater state and energy to the engine controller. U04B6 is stored when those messages arrive but fail plausibility; no carmaker has published its use of the code. Section (e)(2) of CARB 1968.2 requires OBD to confirm that a heated catalyst reaches its target temperature in time, so the check cannot run without valid data. U01B5 marks lost contact. Expect a MIL and higher cold-start emissions.
- What you may notice
- Check engine light on
- Catalyst monitor readiness not set
- Engine may idle longer at raised speed after cold start
- Likely causes
- PossibleHeater control electronics or DC/DC stage faulty
- PossibleHigh-current connection to the heater loose or overheated, giving implausible feedback
- PossibleBus wiring or connector near the hot exhaust damaged
- RareModule and engine controller software not matching
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.