OBD2 code U0018: Medium Speed CAN Communication Bus (+) Low
CAN-High on the medium-speed bus is shorted to ground.
Detected Root Component
Network Component
Observed 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
Possible Causes
- CAN-High shorted to ground
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Tools Required
Interactive Diagnostic
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Parts likely to be the cause (Moteur (général))
Moteur (général)
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Frequently asked questions about code U0018
What does code U0018 mean? ▾
OBD2 code U0018: Medium Speed CAN Communication Bus (+) Low. CAN-High on the medium-speed bus is shorted to ground.
What are the symptoms of code U0018? ▾
Code U0018 may cause: 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. The intensity of these symptoms varies depending on the vehicle and driving conditions.
What causes code U0018? ▾
The most common causes of code U0018 are: CAN-High shorted to ground, Gateway module routing CAN messages incorrectly, CAN terminating resistor (120 Ω) drifted out of spec. A proper OBD2 diagnostic will pinpoint the exact cause.
Is it serious to drive with code U0018? ▾
Yes, code U0018 is critical (Critical). Avoid driving and consult a professional promptly to prevent major damage.
How do I fix code U0018? ▾
Start by reading the code with an OBD2 scanner, then follow the interactive decision tree on this page. Priority causes to check: CAN-High shorted to ground, Gateway module routing CAN messages incorrectly, CAN terminating resistor (120 Ω) drifted out of spec. Difficulty: Medium · Estimated time: 30-60min.