DF852C

What the Code Means

DF852C is a fault memory entry tied to the BODY3-CAN bus (K-CAN9) and indicates the controller has entered Bus OFF: data exchange on the bus has stopped. The code appears in SIB 52 01 25 (BMW 740I 2023, electrical system) in the list of fault memory entries alongside other codes in the same BODY3-CAN Control Module Bus OFF group.

When the K-CAN9 / Body3 CAN bus fails, the modules connected to it stop exchanging data. In that case various codes can be stored in memory, including DF852C and other BODY3-CAN Control Module Bus OFF codes. Severity per the source is moderate, but the effects touch a range of comfort functions and warnings.

Symptoms

Indication and behavior:

• various check control “Drive Fault” warnings;
• restraint system warnings are possible.

Body components:

• windows, doors, and seats may not work.

Data exchange:

• the entire K-CAN9 / Body3 CAN bus may stop exchanging data;
• various codes can be stored in memory, including DF852C and other BODY3-CAN Control Module Bus OFF codes.

Diagnosis and Repair

Step 1. Dealer Visit

The source lists returning the car to the dealer as the fix — in the case described the car was bought as a CPO (certified pre-owned) vehicle, and the issue was repairing front bumper damage. A repair to factory spec beats mediocre work.

Step 2. What Doesn't Work

A DIY repair using filler/bondo and paint won't get you a “like new” result. You can hide the damage behind the license plate, but that doesn't fix the cause — a repair to factory spec is preferable.

Additional diagnostic methods (ISTA, INPA, Tool32), values, and tolerances are not given in the source.