OBD-II code · Network (extended)
U3018 Control Module Input Power Circuit A/B Correlation
Voltages on input power lines A and B do not correlate as expected — one is significantly different from the other.
Is it safe to drive with U3018?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyOne supply line has high resistance
- 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
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–3 h
- Emissions test
- Usually unaffected
- Parts involved
- Module Power A, Module Power B
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.