U04A3Invalid Data Received From Hybrid/EV Battery Interface Control Module C
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- U04A3 concerns interface module C. Such boards do more than measure: they also switch the balancing resistors that bleed charge from individual cells. CARB 1968.2 section (e)(15.2.3) requires hybrid OBD to confirm that cell balancing still holds the cell voltages where intended, and GM checks this per board in 16OBDG02 by closing the odd and even balancing gates in turn and comparing readings, for module C under P1E9E. When the battery controller cannot trust what module C sends, it can neither balance nor judge those cells, so it usually limits power. No manufacturer publishes U04A3 itself. U01A2 marks a silent module C, U033C incompatible software; module D's data fault is filed as U02A0, because U04A4 belongs to the particulate sensor.
- What you may notice
- Hybrid or EV warning, MIL on plug-in hybrids
- Power limited, state of charge shown inaccurately
- Likely causes
- PossibleInterface control module C faulty (measurement or balancing stage)
- PossibleDamaged cell sense lead or connector at module C
- PossibleInterference or contact fault on the pack-internal data link
- 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 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.