Network, generic

U029A Lost Communication With Hybrid/EV Battery Pack Sensor Module

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

The battery pack sensor module is the electronics inside the high-voltage battery that reports pack current and voltage; many designs house it together with the main contactors. U029A means the battery or vehicle controller no longer hears from it. Stellantis documents the code in the battery pack control module of the 2024 Dodge Charger with 400 V electric drive: bulletins 08-026-25 Rev. B and 08-126-25 Rev. B reflash several modules and, if U029A stays, call for a six-minute sleep with the scan tool unplugged before a BPCM soft reset. Audi files U029A00 under address 8C for the 2025 Q5 e and the 2024 Q8 Sportback e-tron. Ford's 2014 code list shows it without the lamp flag. Lacking these values, the car may refuse to drive or charge.

Likely causes

Outdated software in the battery control module or sensor module
Code latched after programming because the network never went to sleep
Moisture or poor contact at the battery low-voltage connector or bus wiring
Battery pack sensor module internally failed

Symptoms

  • Wrench or turtle symbol, reduced power
  • Vehicle does not enable drive or stops charging
  • High-voltage system warning in the cluster

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€0–2,500
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery sensor modulevehicle bus wiring

Related codes

U059BU0335U0111P2D3A

References: static.nhtsa.gov, static.nhtsa.gov, performanceparts.ford.com, static.nhtsa.gov.