Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Blind Spot Monitoring Radar Sensor Controller Unit, Basic Function - GF54.71-P-9891A
Model All (CAR)
With Code 234 (Blind Spot Assist)
except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS))
Example illustration of integrated rear outer radar sensor
Overview
This document contains information on:
- General
- Function
General
The integrated left and right outer rear radar sensor (1, 2) transmits bundled electromagnetic waves as so-called primary signals. Objects in the detection range of the integrated left and right outer rear radar sensor (1, 2) reflect these electromagnetic waves.
Function
The integrated left and right outer rear radar sensor (1, 2) receives the reflected electromagnetic waves (secondary signals) and evaluates them according to various criteria. From this, various information is obtained about the objects.
- Angle or direction to the object
- Distance to the object
- Speed differential
The integrated left and right outer rear radar sensors (1, 2) are connected to the vehicle's network architecture via the periphery CAN (CAN PER).
The integrated left and right outer rear radar sensors (1, 2) operate according to the master-slave principle. The master or slave function can be determined via the connector coding. The master function is defined for the integrated right outer rear radar sensor (2). This means that the integrated left outer rear radar sensor (1) sends its information via the periphery CAN to the integrated right outer rear radar sensor (2). The integrated right outer rear radar sensor (2) evaluates the information from both the integrated left and right outer rear radar sensors (1, 2) and sends corresponding requests and data via the periphery CAN.
| Component description | |||
| Integrated radar sensor, component description | Model 243 with code 234 (Blind Spot Assist) except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) | GF30.30-P-3313B | |
| Model 118 as of model year 2023 with code 234 (Blind Spot Assist) except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) Model 177, 247 as of model year 2022 with code 234 (Blind Spot Assist) except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) |
GF30.30-P-3313L | ||
| Model 167 as of model year 2023 with code 234 (Blind Spot Assist) except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) |
GF30.30-P-3313M |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.