About the OBD2 Auto Emission Scan Tool

OBD2 emissions test fail codes include the catalytic converter, oxygen sensor and gas evaporation system.

All passenger vehicles sold in the United States since the 1996 model year are equipped with an on-board diagnostic system known as OBD2, or OBD II. By using a special tool called an OBD2 scanner, home mechanics can check the emissions system and other car components for trouble codes.

Function

An OBD2 scanner gathers information about a vehicle's emissions and other systems by plugging into a port within its interior. The 16-pin connector reads diagnostic codes which correspond to issues that the manufacturer has specified. Each vehicle has some unique codes, so a model-specific list must be obtained.

OBD2 and Emissions

Many states now require a direct electronic test of a vehicle's emissions components using the OBD2 system. An automobile will fail the emissions test if one of several codes come up, which include those corresponding to the EGR system and the catalytic converters. An OBD2 scanner can be used to diagnose problem areas which could cause the car to fail this test.

Price Range and Models

OBD2 scanner prices can run from $30 for a basic, no-frills model to upwards of $300 for a more sophisticated unit used for real-time performance testing. For vehicles produced on or after 2004, a sub-protocol of OBD2 called CAN is also in place. Scanners capable of reading CAN codes are necessary to adequately prepare a newer model vehicle for emissions testing.

References

• AA1Car: OBD II Emissions Testing and Diagnostic Codes
• The OBD II Home Page: OBD II and Emissions Testing