Lost Communication With Regenerative Braking Control Module
The U0209 code means the vehicle's onboard diagnostic system has detected: Lost Communication With Regenerative Braking Control Module. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $400 - $1,500 (parts and labor)
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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Common Symptoms
- Regenerative braking not functioning
- Reduced braking efficiency warning
- Increased brake pedal effort
- Lower than expected fuel economy
- ABS or brake warning light on
Probable Causes (Ranked by Likelihood)
- Failed regenerative braking module Very High
- CAN bus wiring fault to regen module High
- Brake system sensor failure Moderate
- Software issue in regen controller Low
Step-by-Step Diagnostic Procedure
-
Scan regenerative braking module for fault codes
-
Test CAN bus communication at regen controller
-
Check brake system sensors and wiring
-
Verify regen module power and ground
Frequently Asked Questions
Can I drive with U0209?
Only short distances. Conventional brakes still work but regenerative braking is lost.
What causes U0209?
Typically a failed regenerative braking control module or CAN bus wiring fault.
Is U0209 serious?
Moderately. Conventional brakes function but brake feel may change.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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