OBD2 Code Lookup – Causes & Fixes
Diagnose your car in seconds — before you pay a mechanic. Enter any OBD2 trouble code (P0420, P0300, U0100) and instantly see causes, symptoms, and proven fixes.
Based on official SAE J2012 diagnostic standards used by professional mechanics worldwide, including hybrid and electric vehicles.
Browse DTC Codes by Brand
Find manufacturer-specific diagnostic trouble codes and model-specific repair procedures. Each brand page lists all available OBD-II, chassis, body, and network codes we cover.
Toyota8249 articles
Jeep1604 articles
Chrysler987 articles
Ford741 articles
Lexus66 articles
Hyundai53 articles
Kia52 articles
BYD34 articles
Skoda32 articles
Mitsubishi29 articles
Volvo28 articles
Nissan27 articles
Mercedes-Benz26 articles
Honda25 articles
Chevrolet19 articles
Dodge15 articles
Suzuki14 articles
Volkswagen12 articles
Ram10 articles
GMC8 articles
Audi5 articlesUnderstand Any OBD2 Trouble Code – Check Engine, ABS, Airbag & Hybrid Systems
AutoDTCs.com is a complete OBD2 trouble code lookup for all vehicles. Search and understand diagnostic trouble codes (DTCs), including P, B, C and U codes based on official SAE J2012 standards used by professional mechanics worldwide. Each page includes clear explanations, causes, symptoms, and repair guidance.
Whether your scan tool shows a check engine light, ABS or ESP warning, airbag fault, hybrid battery issue or CAN communication problem, you'll find clear symptoms, common causes, and step-by-step repair guidance for every fault code.
Browse Codes by System
Diagnostic trouble codes are grouped by system. Pick the system that matches your scan tool result to see common subcategories and full code listings.
P-Codes — Powertrain
2,399 codes
Engine, fuel system, ignition, emissions, transmission and hybrid drive faults.
Browse all P-Codes →C-Codes — Chassis
513 codes
ABS, traction control, stability, steering, suspension and driveline faults.
Browse all C-Codes →B-Codes — Body
1,008 codes
Airbag/SRS, body comfort, climate control and interior systems.
Browse all B-Codes →U-Codes — Network & Integration
217 codes
CAN bus, module communication and vehicle integration faults.
Diagnostic Guides
Free step-by-step guides written to professional diagnostic standards — how to test, interpret live data, and find the root cause before replacing anything.
Check Engine Light Flashing vs Steady
A flashing MIL means an active misfire is damaging the catalyst right now. Know when to stop driving.
Multiple DTCs? How to Find the One Root Cause
Most multi-code situations share a single cause — battery, ground, 5V reference, or CAN bus.
Fuel Trim Diagnostics: STFT and LTFT Explained
Both trims positive means lean. Both negative means rich. How to read the numbers and find the cause.
Why Low Battery Voltage Causes Multiple Fault Codes
One weak battery cell can generate codes in six modules simultaneously. Check this before diagnosing anything else.
How to Use OBD2 Freeze Frame Data
The snapshot taken when the fault was stored is more useful than the code itself. How to read it.
How to Perform a Voltage Drop Test
The most revealing electrical test in diagnostics and the most underused. Step-by-step procedure.
OBD2 Trouble Code FAQ
How do I look up a diagnostic trouble code?
Enter the code from your scan tool (for example P0420, P0300 or U0100) into the search box at the top of this page. Each result explains the code meaning, common causes, symptoms, and possible repair steps.
Are P0xxx codes the same for all cars?
Yes. Generic P0xxx codes follow the OBD2 standard and have the same meaning across all makes and models. Manufacturer-specific codes usually use P1xxx ranges or brand-specific B, C, and U codes.
What's the difference between P, B, C and U codes?
P-codes relate to powertrain and emissions systems, B-codes to body and airbag systems, C-codes to chassis systems such as ABS and steering, and U-codes to module communication and CAN network faults.
Can I diagnose hybrid and electric vehicle codes here?
Yes. AutoDTCs.com includes hybrid and EV trouble codes related to high-voltage batteries, inverters, onboard chargers, isolation faults, and other electric drive components.
Do you cover all makes and models?
The information applies to all OBD2-compliant vehicles and includes generic and manufacturer-specific fault codes for brands such as Audi, BMW, Mercedes-Benz, Toyota, Honda, Ford, GM, Volkswagen, Hyundai, Kia, Nissan, BYD, Lexus, Mitsubishi, and more.
Can I drive with a trouble code?
It depends on the code. Some trouble codes indicate minor issues, while others point to serious faults that can affect drivability, safety, or emissions. Always check the code meaning and symptoms before continuing to drive.
How much does it cost to fix a trouble code?
Repair cost depends on the root cause, not just the code itself. Some codes are triggered by simple sensor or wiring faults, while others may require expensive repairs such as catalytic converter, ABS module, or transmission work.