U04A1 Fault Code – Invalid Data Received From Hybrid/EV Battery Interface Control Module A

Car Codes diagnostic trouble code

U04A1Diagnostic priority

Invalid Data Received From Hybrid/EV Battery Interface Control Module ADiagnostic contextPotentially applicable to OBD-II-compliant vehicles; confirm against vehicle VIN, model year and module.Vehicle applicabilityApplicability varies by vehicle, powertrain, model year and control module.

Code interpretation

What U04A1 means

This code indicates Invalid Data Received From Hybrid/EV Battery Interface Control Module A Its precise meaning depends on the reporting control module, complete failure-type suffix, model year, powertrain and software level.

Driver experience

Symptoms you may notice

A stored diagnostic trouble code or related system symptom.

Test, do not guess

Possible causes

Confirm the reporting module, circuit condition, power supply, wiring, component performance and software status.

Evidence-led checks

Recommended diagnostic route

Save the complete scan, confirm the full code and reporting module, then test using model-specific multi-brand technical information.

Capture the evidenceSave the complete all-module scan, code suffixes and freeze-frame data.
Prove the basicsTest battery condition, system voltage, power and grounds.
Identify the reporterConfirm the module that logged the code and check circuit integrity.
Compare live dataReview commanded and actual values under the conditions that set the code.
Test before replacingUse model-specific wiring diagrams, pin tests and technical information.
Verify the repairClear the code only after recording evidence, then confirm it does not return.

Vehicle fitment

Vehicle applicability

Volkswagen ID.4, Volkswagen Tiguan, Volkswagen Golf R

Before clearing

Can the code be cleared?

Clearing a code without fixing the cause removes useful evidence and may only switch the warning off temporarily. Save the full scan first; a permanent or repeatedly returning code needs testing.

A DTC is evidence, not a parts order.

Confirm the suffix, reporting module, model, year, engine and live data before replacing a component.

Verified public evidence

Manufacturer and model coverage

150 public manufacturer records match this search. These records support applicability research but do not replace VIN-specific workshop information.

U04A1Volkswagen Golf R
GOLF R · 2024 · Powertrain

…oolant leak from the cylinder head gasket, low coolant level, visible coolant leak, coolant warning message in instrument cluster; Customer states Electrical System Error Message, U04A1 [42304], U04A5 [42336], and/or…