What are Trouble Codes?

In this project the main requirement of our client was to have a way of identifying what causes his car to malfunction. Through the OBD port we can extract all the details related to the Engine of the vehicle and if your "Check Engine Light" is on, it means your vehicle has one or more OBD II Trouble Codes. The "Malfunction Indicator Lamp" (or MIL ) comes on to warn you when the Onboard Diagnostic System (OBD II) detects a problem that cold cause your vehicle's emissions to exceed 1.5 times the legal limit. 


A trouble code is an alphanumeric value that corresponds to a particular type of fault. The list was originally created by the Society of Automotive Engineers (SAE) for use by all vehicle manufacturers who have to comply with OBD II emissions regulations in the U.S. The same list of basic codes have also been adopted by European and Asian auto makers. The list of trouble codes is subdivided into four basic categories:

• Powertrain ("P") codes (engine, transmission and emissions systems)
• Body ("B") codes (Climate control system, lighting, airbags, etc.)
• Chassis ("C") codes (antilock brake system, electronic suspension and steering systems)
• Network Communications ("U") codes (controller area network wiring bus and modules)These codes are further divided into two major groups:

1. Generic or Global codes, which have a "0" as their second digit to indicate they are common to all makes and models of vehicles. These are the codes that are required for basic emissions fault diagnosis.
2. Enhanced or Manufacturer Specific codes, which have a "1" as their second digit to indicate they are unique to a particular vehicle make or model. These special codes were deemed necessary by the vehicle manufacturers so they could provide additional diagnostic information beyond the basic list of generic OBD II codes for all kinds of faults, not just emissions-related faults.

There are approximately 5,000+ generic OBD2 DTC codes. I have listed down some of it here.

Related to: Fuel and Air Metering

• P0001       Fuel Volume Regulator Control Circuit/Open
• P0002       Fuel Volume Regulator Control Circuit Range/Performance
• P0003       Fuel Volume Regulator Control Circuit Low
• P0004       Fuel Volume Regulator Control Circuit High
• P0005       Fuel Shutoff Valve Control Circuit/Open
• P0006       Fuel Shutoff Valve Control Circuit Low
• P0007       Fuel Shutoff Valve Control Circuit H igh
• P0008       Engine Position System Performance (Bank1)
• P0009       Engine Position System Performance (Bank2)