Quantifying the Impact of Software Updates through First Time Quality in Automotive Production

Vehicle software updates are released more frequently and in increasingly shorter cycles, which places growing pressure on vehicle quality and final assembly line stability. In production environments, software related issues do not remain limited to the digital domain, since errors introduced by software updates can interrupt flashing and commissioning processes, slow down assembly, and increase rework, thereby directly affecting production throughput. Electronic control units are particularly sensitive to software updates because they are flashed and commissioned during vehicle production under strict timing constraints, and changes to flashing sequences, memory structures, configuration parameters, or function definitions can negatively influence commissioning behavior. This paper presents a novel approach where an established quality measure – First Time Quality (FTQ) – is used to quantify the impact of software updates in the final assembly. By comparing FTQ values from production weeks with software updates to reference weeks without software changes, the analysis identifies total FTQ deviations of 7 to 11 percentage points relative to a reference level of approximately 98.6 percent for major software releases. A two-stage root-cause classification combining automated error categorization with expert validation attributes approximately 3 to 4 percentage points of this deviation to software-update-related commissioning errors. Wilson score confidence intervals and Newcombe intervals confirm that these deviations are statistically robust at production-scale sample sizes. FTQ recovery to reference levels typically occurs within one to three weeks after a major release. Using real production data from a vehicle plant, the analysis demonstrates that even comparatively small reductions in FTQ indicate a relevant degradation of production quality and can propagate into downstream quality behavior. These findings show that FTQ is a suitable and production relevant indicator for determining the impact magnitude of software updates in automotive manufacturing and for supporting data-driven decisions in the software release process.