Lost Communication With Vehicle Dynamics Control Module B
What does U0166 mean?
The U0166 code means the vehicle's onboard diagnostic system has detected: Lost Communication With Vehicle Dynamics Control Module B. This is a critical severity code.
Common Symptoms
- Stability control warning light illuminated
- ABS system disabled
- Traction control light on
- Multiple chassis warning messages
- Reduced braking performance in certain conditions
Probable Causes (Ranked by Likelihood)
- Failed secondary vehicle dynamics module Very High
- CAN bus wiring fault between modules High
- Corroded module connector pins Moderate
- Module power supply failure Low
Step-by-Step Diagnostic Procedure
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Verify power and ground at the dynamics control module B
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Check CAN bus wiring between primary and secondary dynamics modules
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Inspect module connector for bent or corroded pins
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Scan all chassis modules for related codes
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Measure CAN bus signal quality at the module connector
Frequently Asked Questions
Can I drive with code U0166?
Only for short distances at reduced speed. The secondary dynamics module handles critical safety functions and should be repaired promptly.
What causes U0166?
A failed secondary vehicle dynamics control module is the most common cause. This code is more common in vehicles with dual stability control modules.
Is U0166 expensive to fix?
Expect to pay between $350 and $1300. The secondary module often requires dealer-level programming after replacement.