A short or open circuit in one of the injectors.

Some brands have dedicated diagnostic software that provides much deeper insight than a generic scanner. For example: for Volkswagen/Audi Group. FORScan for Ford/Mazda. BimmerLink for BMW/Mini. 4. Check Your Fuel Cap

If you have a professional-grade tool, it may simply need a firmware update to recognize newer proprietary codes from recent vehicle models. Steps to Resolve the Issue 1. Note the Numeric Code

"Undefined Fuel-Reserved for Proprietary" isn't a specific part failure; it’s a . By identifying the raw code and researching it through manufacturer-specific channels, you can move past the technical jargon and get straight to the repair.

The computer is detecting pressure that is too high or too low.

Cheap Bluetooth dongles or basic handheld units often lack the licensed library of manufacturer-specific definitions.

Ignore the text "Undefined Fuel-Reserved for Proprietary" and look for the four or five-digit alphanumeric code associated with it (e.g., P1229 or P1602). 2. Use a Brand-Specific Database