Tailpipe vs. OnBoard Diagnostics for Lynwood Emissions Testing Service

June 26, 2011  

When the time rolls around for Lynwood Emissions Service on your vehicle, you just might benefit from a rudimentary understanding of the testing process. Chances are that if you have a car that was manufactured after 1996, your technician/inspector will use the On Board Diagnostic II (OBD II) method to check your emissions. Alternatively, the tailpipe method may just help you pass the emissions test even when your vehicle has problems with the OBD II test.

On Board Diagnostics II

On Board Diagnostics (OBD) is computer technology developed in 1996. The OBD monitors your vehicle’s emission control system, monitoring any increase in pollution (emissions) coming from your vehicle. The OBD is also responsible for monitoring other key engine parts to assure proper operation.

When the OBD detects a problem within your vehicle’s emission controls, a warning light is activated on your dashboard. Because the OBD is capable of catching potential problems early, the test of the system can reveal emissions increase before the tailpipe. Additionally, the OBD test can detect where the specific problem lies within your exhaust system — potentially saving money on unnecessary repairs. Also, as the OBD monitors the entire exhaust system, the tests are much more sensitive than with a tailpipe test.

Occasionally, your vehicle may return the code: “OBD not ready for emissions” (or something to that effect). Don’t despair — this generally means that your OBD has not completed cycling. To remedy the situation, often just driving to allow the computer to complete its inspection cycle will suffice. You should consult your Owner’s Manual or the experts at Carson Cars to determine which parameters must be cycled, and what type of driving (highway, city, etc.) will accomplish this.

Tailpipe Emissions Testing

Occasionally, a service technician will perform a tailpipe emissions test on your vehicle:

  1. If your car was manufactured prior to 1996
  2. If your OBD is not ready for emissions testing

The test consists of placing a probe in the tailpipe to ‘sniff’ emissions. A gas cap test may also be conducted. Unfortunately, the tailpipe testing equipment can only test the emissions from the tailpipe or gas cap giving no indication as to where the actual problem lies. Although, the tailpipe test is nowhere near as sensitive to exhaust system defects as the OBD II.