Code U0113 on the 2021 BMW 3 Series indicates lost communication with an emissions control module. BMW uses dedicated modules for various emissions functions including exhaust aftertreatment, evaporative emissions, and secondary air injection systems.
BMW Emissions System Architecture
BMW's emissions systems are sophisticated, using multiple modules and sensors for precise control. Diesel models have AdBlue/DEF injection modules, while gasoline models may have secondary air injection or enhanced evaporative control modules. These systems communicate with the DME (engine control) and other modules for coordinated emissions management.
Warning Indicators
With U0113 present, the check engine light illuminates and emissions-related fault messages may appear in iDrive. The vehicle may enter a reduced power mode if critical emissions functions are affected. Diesel models may show DEF system warnings. Increased tailpipe emissions result from the disabled control functions.
Diagnostic Approach
Identify which emissions module has lost communication - BMW ISTA provides specific module identification. Common modules include the nitrogen oxide sensor module, secondary air pump control, or DEF injection controller on diesels. Check module power supply, ground, and CAN communication. Verify the DME isn't the source of the communication failure.
Repair Considerations
BMW emissions modules require coding and programming with ISTA or ISTA+. Some modules require VIN-specific configuration. After repairs, verify all emissions monitors reset properly by completing required drive cycles.