Vehicle Error Codes

Search our comprehensive database of OBD-II diagnostic trouble codes. Get detailed causes, symptoms, and step-by-step diagnosis guides.

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Select a code family to explore

Powertrain Codes

Engine, transmission, and drivetrain systems. Most common codes fall here.

Body Codes

Airbag systems, A/C, power windows, lighting, and other body electronics.

Chassis Codes

ABS, traction control, braking, steering, and suspension systems.

Network Codes

CAN bus communication, module communication, and network faults.

Most Searched Codes

The codes drivers look up most often

P0420Catalyst Efficiency Below Threshold

P0171System Too Lean Bank 1

P0300Random/Multiple Cylinder Misfire

P0128Coolant Thermostat Below Temp

P0455EVAP System Large Leak

P0442EVAP System Small Leak

P0440EVAP System Malfunction

P0401EGR Flow Insufficient

P0340Camshaft Position Sensor Circuit

P0700Transmission Control System

Code Format

P

System

0

Type

4

Subsystem

2

Fault

0

Fault

What is an OBD-II Code?

OBD-II codes are standardized diagnostic trouble codes that your vehicle's computer generates when it detects a problem. Each code starts with a letter (P, B, C, or U) followed by four digits that identify the specific issue.

When your check engine light comes on, an OBD-II scanner reads these codes to help identify what's wrong. Our database explains each code in plain language with community-verified fixes.