Diagnostics & Reference Tools
Free diagnostic and reference tools for understanding common vehicle problems before opening a repair manual. Use these apps to check OBD2 code structure, dashboard warning lights, fuse references, wiring colors, spark plug gaps, bolt patterns, and basic symptoms.
Car Problem Diagnoser – Symptom Troubleshooting Guide
Car Problem Diagnoser Select a symptom to see the likely system, probable causes, and recommended first diagnostic steps — a quick DIY starting point. Symptom....
Car Wiring Color Codes – Quick Reference Tool
Car Wiring Color Codes Look up common automotive wire colors and their typical circuit functions — a quick reference for diagnostics and accessory installation. Wiring....
Dashboard Light Colors – Red, Amber & Green Meaning
Dashboard Light Colors Guide Learn what red, amber, yellow, green, and blue dashboard lights mean and exactly how urgently you should act on each. Dashboard....
Dashboard Warning Lights Guide – Symbol Identifier
Dashboard Warning Lights Guide Select any dashboard warning light to instantly understand what it means, how urgent it is, and what to do next. Warning....
Fuse Color Code Chart – Amperage Identifier
Fuse Color Code Chart Identify any automotive blade fuse by color or amperage — a fast reference for every fuse in your fuse box. Fuse....
OBD-II Code Lookup — P, B, C & U Code Meaning
OBD-II Code Lookup Look up the meaning of any OBD-II diagnostic trouble code (DTC). Enter a P0xxx, P1xxx, B0xxx, C0xxx, or U0xxx code to see....
OBD2 Code Explainer – Understand P0420 & More
OBD2 Code Structure Explainer Type any OBD-II code to understand its structure — system, generic vs manufacturer, and sub-system — before searching for repair info.....
OBD2 Readiness Monitors – Pass Your Emissions Test
OBD2 Readiness Monitors Guide Understand OBD-II readiness monitors and why ‘not ready’ fails an emissions test — with drive cycle guidance for each monitor. Readiness....
Spark Plug Gap Guide – Standard Settings & Adjustment
Spark Plug Gap Guide Look up the correct spark plug gap range for your engine type and convert any gap measurement between inches and millimeters....
Wheel Bolt Pattern Lookup – PCD & Stud Count Guide
Wheel Bolt Pattern Lookup Select a bolt pattern (PCD) to instantly see the stud count, pitch circle diameter in mm and inches, and common vehicle....
