U0118 Reserved Communication Code
The U0118 code is a reserved diagnostic trouble code under the SAE J2012 standard, meaning it has no universally defined meaning for generic OBD2 systems. It falls within the range U0100-U02FF, which covers CAN bus communication issues between electronic modules. Since it is reserved, it is not assigned to any specific fault in the current standard and is held for future expansion or proprietary manufacturer use. In practice, this code may appear due to a scanner misread, software corruption in a control module, or undocumented manufacturer-specific applications. It should not be treated as a standard communication fault without further investigation.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Reserved code with no defined failure causes under SAE J2012
- Possible undocumented proprietary use by a specific manufacturer
- Scanner reading error; verify with updated diagnostic equipment
- Control module software corruption generating an invalid code
3. Symptoms You Will Notice
- Check Engine Light illuminated
- No drivability issues typically present unless accompanied by other codes
4. Step-by-Step Diagnosis
Confirm the code with a professional-grade scan tool that supports manufacturer-specific codes
Check for any other stored codes that may indicate a real communication problem
Update the scan tool software and re-scan to rule out a reading error
If the code persists and no other issues are present, consult manufacturer service information for proprietary definitions
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive with this code alone, as it is reserved and not linked to a specific malfunction. However, if other codes or symptoms are present, have the vehicle inspected.
How much does it cost to fix?▼
Since U0118 has no defined cause, diagnostic costs typically range from $100 to $200 for labor. If a software update or module reprogramming is needed, costs can increase to $300-$600.