OBD-II code · Network (extended)
U3009 Control Module Ground B
Control Module Ground B: the control module has detected this fault condition.
Is it safe to drive with U3009?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyGround stud corroded
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Module Ground B, Ground Strap
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.