OBD Codes.On-Board Diagnostic (OBD) trouble codes are one way your vehicle communicates with a mechanic. Every car built since 1996 has an OBD computer system that monitors and identifies issues. In particular, it looks for issues that may result in harmful and polluting emissions from exhaust gases. When this system identifies an issue it turns on the check engine light and records an OBD code.
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Diagnosing and RepairOBD-II codes are computerized trouble codes specific to all OBD-II compliant vehicles. These are generally cars, SUVs, light trucks, etc. that are made and/or sold in the US since 1996. The codes are used for automotive diagnosing and repair.
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OBD-II Diagnostic ScannerOBD-II provides monitoring for various systems. They include the engine control module, body, chassis, etc. When you look at the code, you can immediately tell which system has a fault-based issue by how it appears on the diagnostic scanner.
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Explaining OBD-II Codes
The First Character (Letter)
All OBD-II codes begin with a letter that denotes the part of the vehicle that has a fault.
P – Powertrain. It includes the engine, transmission and all the associated accessories.
U – Network & Vehicle Integration. These are functions that are managed and shared by onboard computer systems.
B – Body. These are parts mainly found in the passenger compartment area.
C – Chassis. It covers mechanical systems and functions like steering, suspension, and braking.
The Second Character (Number)
The first letter is usually followed by a number. This number can only be ‘0’ or ‘1’.
0 – If it’s a ‘0’ then the code is a standardized (SAE) code; also known as generic code
1 – If it’s a ‘1’ then you’re looking at a manufacturer-specific code
The Third Character (Number)
This number denotes the particular vehicle system that has a fault. There are eight systems in total:
0 – Fuel and air metering and auxiliary emission controls
1 – Fuel and air metering
2 – Fuel and air metering (injector circuit)
3 – Ignition systems or misfires
4 – Auxiliary emission controls
5 – Vehicle speed control and idle control systems
6 – Computer and output circuit
7 – Transmission
The Fourth And Fifth Characters (Number)
The final piece of a DTC is a two-digit number. This number defines the exact problem that you’re dealing with. It can be any number between 0 and 99.
All OBD-II codes begin with a letter that denotes the part of the vehicle that has a fault.
P – Powertrain. It includes the engine, transmission and all the associated accessories.
U – Network & Vehicle Integration. These are functions that are managed and shared by onboard computer systems.
B – Body. These are parts mainly found in the passenger compartment area.
C – Chassis. It covers mechanical systems and functions like steering, suspension, and braking.
The Second Character (Number)
The first letter is usually followed by a number. This number can only be ‘0’ or ‘1’.
0 – If it’s a ‘0’ then the code is a standardized (SAE) code; also known as generic code
1 – If it’s a ‘1’ then you’re looking at a manufacturer-specific code
The Third Character (Number)
This number denotes the particular vehicle system that has a fault. There are eight systems in total:
0 – Fuel and air metering and auxiliary emission controls
1 – Fuel and air metering
2 – Fuel and air metering (injector circuit)
3 – Ignition systems or misfires
4 – Auxiliary emission controls
5 – Vehicle speed control and idle control systems
6 – Computer and output circuit
7 – Transmission
The Fourth And Fifth Characters (Number)
The final piece of a DTC is a two-digit number. This number defines the exact problem that you’re dealing with. It can be any number between 0 and 99.