The Full Wiki

More info on Malfunction Indicator Lamp

Malfunction Indicator Lamp: Wikis

Advertisements

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

(Redirected to Indicator lamp article)

From Wikipedia, the free encyclopedia

A Malfunction Indicator Lamp, this one labeled "Service Engine Soon".
A MIL with an engine symbol.

A malfunction indicator lamp (MIL), commonly referred to as the "Check Engine Light" is an indicator of malfunction of the computerized engine management system. It is found on the instrument console of most automobiles. When illuminated, it is typically either a amber or red color. On vehicles equipped with OBD-II, the light has two stages: steady (indicating a minor fault such as a loose gas cap or failing oxygen sensor) and flashing (indicating a severe fault, that will eventually destroy the catalytic converter, such as a misfire). When the MIL is lit, the engine control unit stores a fault code related to the malfunction, which can be retrieved with a scan tool and used for further diagnosis. The malfunction indicator lamp is usually labeled with the text check engine, service engine soon, check engine soon, or a picture of an engine.

The MIL appeared in the early 80s along with computerized engine controls. Even the earliest systems, such as GM's CCC (Computer Command Carburetor) system had self diagnosis functionality. When the computer detected a fault, it illuminated the MIL. Up until OBDII, on most cars the MIL could output codes, when two pins on the ALDL are jumped, the light would flash the codes, for instance (blink) (pause) (blink) (blink) for code 12. Some manufacturers retained this feature even after OBDII, such as Honda.

Contents

"Trouble" indicator

Some older vehicles had a single indicator labeled "trouble" or "engine"; this was not an MIL, but a warning light meant to indicate serious trouble with the engine (low oil pressure, overheating, or charging system problems) and an imminent breakdown. This usage of the "engine" light was discontinued in the mid-1980s, to prevent confusion with the MIL.

Odometer triggering

Some vehicles made in the late 80s and early-to-mid 90s have a MIL that illuminates based on the odometer reading, regardless of what is going on in the engine. For example, in several Mazda models, the light will come on at 80,000 miles and remain lit without generating a computer trouble code. Volvo had a light labeled "Lambda", lambda sond being another name for oxygen sensor. This was done in order to remind the driver to change the oxygen sensor.

All American production 1973–1976 Chrysler/Plymouth/Dodge/Imperial cars had a similar odometer-triggered reminder: "Check EGR", which was reset after service at a Chrysler dealership. The MIL light is also triggered prior to starting the engine, along with other lamps such as the coolant lamp and battery lamp, to allow a visual check to ensure the lamp is working and not burned out. The lamp will turn off once the car is started if no trouble persists.

Ethanol

Higher amounts of methanol/ethanol (or other additives) than the engine can handle efficiently may also trigger the malfunction indicator lamp (see E85). These burn differently from gasoline, and the EFI system may mistakenly interpret the oxygen sensor's readings as being incorrect. Oxygenated gasoline (ie. in California) may also cause this problem ("too lean" or "oxygen sensor" failure) in early EFI systems.

See also

External links

Advertisements

A malfunction indicator lamp (MIL), sometimes referred to as the "Check Engine Light" is an indicator of the internal status of a car engine. It is found on the instrument console of most automobiles. When illuminated, it is typically either a red or amber color. On vehicles equipped with OBD-II, the light has two stages: steady (indicating a minor fault such as a loose gas cap or failing oxygen sensor) and flashing (indicating a severe fault, such as catalytic converter problems or engine misfire). When the MIL is lit, the engine control unit stores a fault code related to the malfunction, which can be retrieved with a scan tool and used for further diagnosis. The malfunction indicator lamp is usually labeled with the text check engine, service engine soon, check engine soon, or a picture of an engine.

The MIL became required on passenger cars in the United States due to emission control legislation in California, with the intention that the light would illuminate if there was a problem which would cause the vehicle to have excessive pollutant emissions. The owner would be aware that the emission control system needed to be serviced, and would be prevented from renewing their registration in the state of California.Template:Fact In most states and regions that require emissions inspections, a lit MIL on an OBD-I or OBD-II vehicle will cause the vehicle to fail the inspection.

Contents

"Trouble" indicator

Some older vehicles had a single indicator labeled "trouble" or "engine"; this was not an MIL, but a warning light meant to indicate serious trouble with the engine (low oil pressure, overheating, or charging system problems) and an imminent breakdown. This usage of the "engine" light was discontinued in the mid-1980s, to prevent confusion with the MIL.

Odometer triggering

Some vehicles made in the late 80s and early-to-mid 90s have a MIL that illuminates based on the odometer reading, regardless of what is going on in the engine. For example, in several Mazda models, the light will come on at 80,000 miles and remain lit without generating a computer trouble code. This was done in order to remind the driver to change the oxygen sensor.

All American production 1973-1976 Chrysler/Plymouth/Dodge/Imperial cars had a similar odometer-triggered reminder: "Check EGR", which was reset after service at a Chrysler dealership. The MIL light is also triggered prior to starting the engine, along with other lamps such as the coolant lamp and battery lamp, to allow a visual check to ensure the lamp is working and not burned out. The lamp will turn off once the car is started if no trouble persists.

Ethanol

Higher amounts of methanol/ethanol (or other additives) than the engine can handle efficiently may also trigger the malfunction indicator lamp (see E85). These burn differently from gasoline, and the EFI system may mistakenly interpret the oxygen sensor's readings as being incorrect. Oxygenated gasoline (ie. in California) may also cause this problem ("too lean" or "oxygen sensor" failure) in early EFI systems.

See also


Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message