U0209
Lost Communication With Seat Control Module B
Network communication
Generic OBD-II
Low
What it means
U0209 sets when a module loses data-bus communication with Seat Control Module B — the module that operates power adjustment, memory, and related comfort features for that seat. The engine and safety systems are unaffected, so you can drive normally; only that seat's powered functions go down.
Low
Can I keep driving? Yes — power seat adjustment and memory for that seat stops working, but the engine, brakes, and steering are unaffected, so you can keep driving until it's convenient to repair.
Common symptoms
What you'll notice
- Power seat adjustment stops working for that seat
- Seat memory positions won't recall
- Heated/ventilated seat or powered lumbar (if module-controlled) may not respond
- A seat-system warning message may appear
Common causes
Most likely first
- Corroded, loose, or damaged connector at the module or an inline body connectorLikely
- Chafed, broken, or shorted wiring in the communication (CAN) circuit to the moduleCommon
- Loss of switched power or ground to the affected moduleCommon
- Water intrusion into a body/door connector or the module itselfLess often
- Failed module with an internal faultLess often
- A wider data-bus problem pulling the network downLess often
How to diagnose & fix
Work through it in order
- Scan every module and note all U-codes first — several codes together point to a bus or gateway fault rather than one module.
- Inspect the connector and harness at the module for corrosion, bent pins, water, or chafing.
- Confirm the module has good switched power and a clean ground with a multimeter.
- Check communication-bus continuity and resistance from the module back to the network.
- If wiring and power are good, the module is likely faulty — replace and program/configure it as required.
- Clear the code, recheck, and confirm the affected feature works and the code stays gone.
FAQ
Quick answers
Is it safe to drive with U0209?+
Yes. U0209 affects only power seat adjustment and memory for that seat; it has no effect on the engine, brakes, or steering, so the car starts and drives normally. Repair it to restore the feature.
Can I just clear U0209?+
You can clear it, but if the module is still off the bus the code returns almost immediately. Fix the wiring, connector, power/ground, or module first, then clear and confirm the feature works.
Related codes
Often seen with U0209
Read & clear U0209 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