Network, generic

U0348 Software Incompatibility With Hybrid/EV Battery Interface Control Module O

Check engine lightUsually off
EmissionsRelevant
Drive cycleNot required
Limp modePossible

O stands for a fifteenth board; no public document links U0348 to a vehicle. That the software inside a cell monitoring unit can itself be the problem is shown by Honda's recall 15V602 of October 2015: in 6,786 Accord Hybrids of 2014–2015 the cell voltage sensor (CVS) could misread electrical noise from inverter and motor circuits, a side effect of a change made for digital TV reception in Japan, and switch the car into a fail-safe EV mode limited to about 40 mph, with the engine off. Dealers installed new hybrid system software, which Honda says does not affect emissions or fuel economy. Honda uses no letter codes for the CVS. U01AE flags a silent O, U04AF corrupted data.

Likely causes

Firmware of the monitoring unit itself faulty and superseded
Board O missed a released software update
Pack boards on different update levels after a partial repair

Symptoms

  • Fail-safe mode with reduced speed and power
  • Engine switched off, electric drive only until the battery is drained
  • Hybrid warning with audible alert

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€0–500
Time0.3–2 h

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

Parts involved

hv battery interface module o

Related codes

U01AEU04AFU0347U0349

References: static.nhtsa.gov, static.nhtsa.gov.