Smart Key Module Communication Bus Off
The U0689 code means the vehicle's onboard diagnostic system has detected: Smart Key Module Communication Bus Off. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $200 - $1,000
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
- Push button start not working
- Key fob not detected
- Immobilizer warning light on
- Door handles not unlocking with proximity
Probable Causes (Ranked by Likelihood)
- Smart key module internal fault Very High
- Key fob battery low or dead High
- Antenna ring around ignition damaged Moderate
- CAN bus communication to smart key module lost Low
Step-by-Step Diagnostic Procedure
-
Replace key fob battery as first step
-
Test with second key fob if available
-
Check antenna ring resistance
-
Verify smart key module communication on network
Frequently Asked Questions
Can I drive with U0689?
Check the severity. If it affects safety systems like stability control or braking, limit driving to short distances. Comfort features like heaters or parking assist are safe to drive with.
What causes U0689?
Most commonly a faulty smart key module or damaged wiring in the communication circuit to that module.
How much does it cost to fix U0689?
Typical repair costs range from $200 - $1,000 depending on whether the module or just wiring needs repair.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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