U0233
Lost Communication With Side Obstacle Detection Control Module B
Communication network
Generic OBD-II
Low
What it means
U0233 means the network has lost communication with side obstacle detection control module 'B' — the second blind-spot / side-obstacle monitor (typically the opposite side from module A). The vehicle drives normally, but that side's blind-spot alerts stop working.
Low
Can I keep driving? Yes — the car drives normally, but blind-spot and side-obstacle alerts are disabled, so check your mirrors and get it fixed.
Common symptoms
What you'll notice
- Blind-spot / side obstacle monitoring stops working or shows a 'system unavailable' message
- A warning light for the feature (or the check-engine light) comes on
- Blind-spot indicators on one side stay off
- The affected module doesn't respond on a full-system scan
Common causes
Most likely first
- Damaged wiring or a loose/corroded connector at the module (often in a rear quarter-panel or bumper)Likely
- Loss of power or ground to the moduleCommon
- A CAN bus fault (open, short, or high resistance) on that circuitCommon
- Water intrusion or corrosion at the module or its connectorLess often
- Failed module (least common — rule out wiring and power first)Less often
How to diagnose & fix
Work through it in order
- Scan all modules and note exactly which one reports the code to locate the affected segment.
- Inspect the wiring and connector at the module (often in a rear quarter-panel or bumper) for damage, chafing, or corrosion.
- Check power and ground to the module with the connector loaded.
- Test the CAN bus circuits to the module for opens, shorts, or high resistance.
- If wiring and power test good, suspect the module itself. Repair and re-test.
FAQ
Quick answers
Is it safe to drive with U0233?+
Mechanically yes — the engine and transmission are unaffected. But blind-spot / side obstacle monitoring won't work, so don't rely on it and get the wiring checked.
Can I just clear U0233?+
You can, but if the module is still off the bus the code returns within a few drive cycles. Fix the wiring or power fault first.
Related codes
Often seen with U0233
Read & clear U0233 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX