North Bay Nissan


You & Your Vehicle


"Check Engine Lights"

WHY?!?! In 1996 the federal government required more sophisticated Emission Controls on vehicles sold in the United States. These systems are named OBD II (On Board Diagnostics, 2nd Generation). Part of these required systems were put in place to standardize languages used to describe various parts of your vehicles Diagnostic. Trouble Codes (DTC'S) and the type of plug used to connect to diagnostic equipment.

It is likely you are not interested in some of these details. What you should care about is that little yellow/amber colored light, when on that reads "Service Engine Soon." Check Engine Light or Malfunction Indicator Light. This light has, in many cases, has caused people to stop driving, becoming worried about their vehicle and possibly upsetting changes to their daily schedules when it may not be necessary. There are several levels of concern that you should know and understand about this little light.

First, this light can sometimes be erratic, coming on and staying on for a day or two, or even a few weeks at a time, then going off for a while and then like magic here it is again, back on! This usually is caused by an erratic operation of one or more of your Emission Control components. As your vehicles ECM (engine control module) is constantly performing internal self tests, it may recognize a part operating outside of its normal range for a length of predetermined time, it will turn that light on. When it sees that the part is working OK again and is satisfied that it is OK, it turns the light off again (the system should store a code (DTC) even if the light has gone out. This can be frustrating for you as a customer, as well as your professional Service Technicians. This can be an issue that still needs diagnosis and a repair, often causing an automatic failure during a Smog Check and with excessive emissions resulting in Air Pollution.

There are many items that can cause this light to come on. It can be something as simple as the fuel cap not being fully tightened to numerous or complex combination of sensors, switches, valves, catalytic converters, fuel injection components, even transmission and some systems that you might think have nothing to do with how the vehicle runs and performs. In many cases a repair may be made and the vehicle test driven only to have the light back on again for a different reason. In many of our vehicles even low and/or dirty oil can turn on a light.

When you make an appointment with us for maintenance/service and or repairs and this light is on, please be sure to let your service writer know of existing issues and be prepared to answer some questions regarding what conditions were taking place when the light came on, this is especially important when we are trying to make the repair, to know when the light is acting erratic and turning off and on.

The next level of this little light is for it to come on and stay on steady, while driving. This means that something is amiss and again needs diagnosis and repairs both for Smog Check purposes and Air Pollution. If it is a problem that is serious enough, it could put your vehicle into Fail Safe Mode which will drastically reduce performance, again storing a code or multiple codes indicating which system is failing.

The last level is a flashing/blinking light. This is usually accompanied by a noticeable reduction in vehicle performance and is a serious indicator of repairs being needed. You should get your vehicle to a Nissan dealer as soon as possible with as little driving as possible to avoid doing damage to your engine, transmission or other components. Things such as outside temperature, road speed, engine speed (RPM), how long of a drive does it take to duplicate the situation. This information is needed so we can accurately duplicate and analyze the identical conditions you report, and repaired to your expectations.

If you should have any other questions regarding this little annoying light, you may reference your owner's manual or contact one of your professional Service Technicians To pre-view our specials please click here. Our job is to help you protect your investment; keep a safe and reliable vehicle that will give you years of enjoyment.

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