U0446: Invalid BCM 'E' Data
The U0446 code indicates that a control module (typically the PCM or another module on the CAN bus) has received invalid, inconsistent, or out-of-range data from the Body Control Module (BCM) designated as 'E'. While physical communication exists, the data integrity (checksum, rolling count, logical values) has failed, preventing proper interpretation of parameters such as lights, locks, wipers, and other body systems managed by that specific BCM.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Internal BCM 'E' failure (hardware or software/calibration corruption)
- Loose, corroded, or damaged connections at the BCM 'E' connector
- Excessive battery voltage variations (low voltage or spikes) affecting module logic
- Software version incompatibility between modules after a partial reprogramming
3. Symptoms You Will Notice
- Malfunctioning exterior or interior lights
- Power lock or window issues
- Wiper or washer system problems
- Other body electrical system failures
- Check Engine Light or other warning lights illuminated
4. Step-by-Step Diagnosis
Scan all modules for related codes and verify U0446 is current
Inspect BCM 'E' connector for corrosion, damage, or loose pins
Check CAN bus wiring for shorts, opens, or high resistance
Monitor battery voltage and charging system for stability
Test BCM 'E' communication with a scan tool; if no response, suspect internal failure
Check for software updates or TSBs related to BCM 'E' communication
5. Frequently Asked Questions
Is it safe to drive?▼
The vehicle may still be drivable, but electrical functions like lights or wipers could fail unexpectedly. It is recommended to diagnose and repair promptly to avoid safety hazards.
How much does it cost to fix?▼
Diagnosis typically costs $100-$200. Repair costs vary widely: a loose connection may be under $100, while BCM replacement and programming can range from $500 to $1,200.