Emission Control System

Check Engine Light | On-Board Diagnostics | Oxygen Sensor
 
Complete Car Maintenance: Check Engine Light
The CHECK ENGINE LIGHT on your instrument panel can light up for a wide variety of reasons. Drivers often ignore the CHECK ENGINE LIGHT when it illuminates. According to a national survey, more than one in 10 drivers admit they drive with the CHECK ENGINE LIGHT on—approximately 20 million vehicles per week. A third of these said they operated their cars for more than three months even though they knew the light—a dashboard indicator that signals a malfunction in a vehicle's engine, transmission or emissions systems—was illuminated.
 
Maintenance and Care:

If your vehicle is equipped with onboard diagnostics, the CHECK ENGINE LIGHT (in some models, the SERVICE ENGINE SOON light) should illuminate briefly once you turn the ignition to on, then go out after a few seconds. It should remain out while you are driving. Do not ignore the light if it comes on while driving the vehicle—there could be a simple solution, or it could be a warning sign of a much more severe condition. AAMCO centers can diagnose whatever the problem may be.

Complete Car Maintenance: On-Board Diagnostics
The on-board diagnostics computer system known as OBD II has been mandatory on vehicles built since 1996 and OBD1 since 1979. It uses a network of computer sensors to monitor the vehicle’s operating conditions.
 
Maintenance and Care:

Often the CHECK ENGINE LIGHT (in some models, the SERVICE ENGINE SOON light) will light to alert you to problems detected by the computer. The on-board computer stores a diagnostic trouble code when it detects a problem; the trained technicians at AAMCO can access this information using a scanning device connected to the vehicle’s computer.

Complete Car Maintenance: Oxygen Sensor
If you have ever driven a vehicle or behind a vehicle with a “rotten egg” smell, it can be due to a faulty oxygen sensor. The oxygen sensor is in the exhaust system, and in part provides information to the on-board computer to help calculate fuel delivery to the engine.
   
Maintenance and Care:
The oxygen sensor should be replaced at the interval indicated in your owner’s manual, or if there are signs of a faulty oxygen sensor. The signs include that rotten egg smell from the exhaust, poor gas mileage, failing an emissions test, and poor acceleration.
 
Some vehicles also have an oxygen sensor light that appears when the sensor needs replacement, or it can also cause the CHECK ENGINE LIGHT (in some models, the SERVICE ENGINE SOON light) to come on. If the light remains lit, do not ignore it. There could be a simple solution, or it could be a warning sign of a much more severe condition. AAMCO centers can diagnose whatever the problem may be.