Network & communication Enriched, not yet reviewed Lights the check engine lamp

U04AF: Invalid Data Received From Hybrid/EV Battery Interface Control Module O

Standardized SAE J2012 code · U04xx — Invalid data received

What does U04AF mean?

A receiving module detected implausible data from hybrid/EV battery interface module O. Cell-voltage, current or temperature values fail plausibility checks against other inputs and are rejected.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

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

High Module internal fault or sensor input drift
Medium Software version mismatch after replacement
Low Gateway module routing CAN messages incorrectly

Likelihood is a general estimate across vehicles; your make and model may differ.

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Describe your U04AF problem

At a glance

System: Network & communication
Repair difficulty: Hard · Workshop recommended
Typical labour: 1–5 h
Typical cost: €200–€2,500
Emissions-related: No
Limp mode: Possible — power may be reduced
After the repair: A drive cycle is needed before the monitor reports ready

Components involved

Hv battery interface module o

Reading this code

Network & communication codes are stored in modules a basic OBD-II reader often cannot reach; use a tool with full-system access.

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Sources

The explanation was compiled from the cited sources but has not had an individual review yet.

Data: OBDex (CC0), revision 3eca5de.

What does U04AF mean?

Symptoms

Common causes

U04AF in the community

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