obd-diagnosis

Interpret OBD-II diagnostic trouble codes and classify their severity.

1|1|Updated Nov 21, 2025

Search Tags:#obd-ii #car diagnostics #trouble codes #automotive repair #check engine light #dtc

Ready to run

npx skills add https://github.com/hmls-autos/hmls --skill obd-diagnosis

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: obd-diagnosis
Source: https://github.com/hmls-autos/hmls/tree/main/apps/agent/.skills/obd-diagnosis
Command: npx skills add https://github.com/hmls-autos/hmls --skill obd-diagnosis

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill helps interpret cryptic OBD-II diagnostic trouble codes (DTCs) that illuminate a vehicle's check engine light, providing clear explanations and actionable guidance.

Core Features & Use Cases

Code Interpretation: Breaks down the meaning of specific DTCs based on their format (P, B, C, U codes).
Diagnostic Guidance: Offers a structured approach to identifying potential root causes and symptoms.
Severity Assessment: Classifies the urgency of the issue (Critical, High, Medium, Low).
Use Case: A customer reports their check engine light is on and provides the code "P0420". This Skill can explain that it relates to catalyst system efficiency, suggest likely causes like exhaust leaks or a failing catalytic converter, and advise on the severity and next steps.

Quick Start

Interpret the OBD-II code P0300 and provide diagnostic guidance.

Frequently Asked Questions about obd-diagnosis

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I interpret OBD-II diagnostic trouble codes when my check engine light is on?▼

OBD-II diagnostic trouble codes are interpreted by breaking down their alphanumeric structure to identify specific vehicle faults. The process decodes P, B, C, and U code formats to provide explanations of powertrain, body, chassis, and network communication issues.

What is the best way to diagnose the root cause of a specific car trouble code like P0420?▼

The best way to diagnose car trouble codes is to use a structured approach that identifies potential root causes and symptoms. This method evaluates catalyst system efficiency issues, suggests likely causes like exhaust leaks, and advises on next steps.

How does severity assessment work for automotive repair codes?▼

Severity assessment for automotive repair codes works by classifying the urgency of the identified vehicle fault into Critical, High, Medium, or Low categories. This classification helps prioritize repair actions based on the specific diagnostic trouble code.

Can I get diagnostic guidance for network communication codes and chassis codes?▼

You can get diagnostic guidance for network communication codes and chassis codes. The interpretation covers all OBD-II scopes, providing structured diagnostic approaches and explanations for U codes and C codes alongside standard powertrain faults.

What do the different OBD-II code families mean for vehicle diagnostics?▼

OBD-II code families indicate the specific subsystem experiencing a fault: P for powertrain, B for body, C for chassis, and U for network communication. Understanding this structure is required for accurate vehicle diagnostics and repair prioritization.