OBD light on
All modern vehicles are equipped with an onboard computer diagnostic
system (OBDII) that constantly monitors your vehicle's major operating
systems and most
importantly the power-train (engine and
transmission). The main purpose of monitoring these systems is to insure
that the vehicle is operating at top
efficiency with the lowest possible
emissions. As fuel economy and emission control has become increasingly
important and complex, your vehicle's electronics
systems need to constantly adjust and
fine-tune various parameters according to driving conditions (such as
vehicle load, temperature, and air/fuel mix to
name just a few). When the computer reads
that any of these parameters do not fall within the acceptable range for
operating the vehicle, your CHECK ENGINE
LIGHT is lit to warn you that you may have
a serious problem and to take your vehicle to a certified technician -
such as your local AAMCO technician - to
check the faults and restore it to
If the check-engine light comes on, here are some tips on what you should do:
- Look for a serious problem that requires immediate attention. Check your dashboard gauges and lights for indications of low oil pressure or overheating. These conditions mean you should pull over and shut off the engine as soon as you can find a safe place to do so. On some cars, a yellow "check engine" means investigate the problem, while a red "check engine" means stop right now.
- Try tightening your gas cap. This often solves the problem. Keep in mind that it may take several trips before the light resets. Some vehicles have a separate indicator that warns of a loose gas cap before the condition sets off the "check engine" light.
- Reduce speed and load. If the "check engine" light is blinking or you notice any serious performance problems, such as a loss of power, reduce your speed and try to reduce the load on the engine. For example, it would be a good idea to stop towing a trailer. Have the car checked as soon as possible to prevent expensive damage.
- Contact OnStar, if available. If you have a 1997 or later General Motors vehicle equipped with OnStar and an active OnStar subscription, contact an advisor who can read the trouble code remotely and advise you about what to do.
- Have the code read and the problem fixed. If you want to diagnose the malfunction yourself, you can buy a scan tool at most auto parts stores. Prices range from about $40 to several hundred, depending on the model and the features. The tools come with instructions on how to hook them up and decipher the codes. But unless you have a good knowledge of automotive diagnostics, you're probably better off taking the vehicle to a professional. Some automotive parts stores will read and interpret the code for you without charge. Unless there is an easy fix, they may simply refer you to a mechanic.
- Don't go for a state emissions test. In a late-model car, an illuminated "check engine" light probably is a sure sign your car will fail the test. In some states, it's an automatic failure, even if the problem was nothing more than a loose gas cap. By the way, don't bother trying to fool the inspection station by disconnecting the battery or using any other method to erase the trouble code and turn off the "check engine" light. Your vehicle's computer will let the inspection station know that its codes have been erased, and you'll just have to go back again.
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Jan 01, 2012 |
BMW X5 Series Cars & Trucks