Check engine light
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A check engine light or malfunction indicator lamp (MIL), is a tell-tale that a computerized engine-management system used to indicate a malfunction. Found on the instrument panel of most automobiles, it usually bears the legend engine,[1] check engine, service engine soon, maintenance required, emmiss maint,[2] or a pictogram of an engine—and when illuminated, it is typically an amber or red color.
The light generally[3] has two stages: steady (indicating a minor fault) and flashing (indicating a severe fault). When the MIL is lit, the engine control unit stores a fault code related to the malfunction, which can be retrieved—although in many models this requires the use of a scan tool. This warning light can indicate almost anything from a loose gas cap to a serious knock in the engine.[4]
In the United States, specific functions are required of the MIL by EPA regulations.[5]
Car warning lights and symbol explanation In the above for reference .Car warning lights are visual indicators on a vehicle's dashboard that are designed to alert the driver to potential problems with the car. When a warning light illuminates, it indicates that there is an issue that needs to be addressed. The warning lights are represented by symbols, which vary between manufacturers and models, and can indicate problems with the engine, emissions system, brakes, battery, oil pressure, and other critical systems.Cite error: A <ref> tag is missing the closing </ref> (see the help page).[6][7]
Odometer triggering
Some vehicles manufactured from the late 1990s to mid 2000s have a MIL that illuminates based on the odometer reading, regardless of engine operation. For example, in several Mazda models, the light will come on at 80,000 miles (130,000 km) and remain lit without generating a computer trouble code.[citation needed] 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. Some American-built 1973–1976 Chrysler Corporation vehicles had a similar odometer-triggered reminder: "Check EGR", which was reset after service at a Chrysler dealership.
Other triggering
The MIL is also illuminated prior to starting the engine, along with other tell-tales on the dashboard, to demonstrate that the lamp is working and not burned out. The lamp will turn off once the car is started if no monitored faults exist. The MIL will also illuminate if the engine has been cranked but failed to start after returning the ignition to "on". In most modern vehicles this is usually due to not giving the engine enough cranking time to start. In pre-fuel injection years many cranking attempts were sometimes required to start the car. If the engine fails to start on the second or third attempt then an actual visual check of the engine could be required. If the engine suddenly stalls or is triggered by an overload, such as on a manual transmission car, the MIL will also illuminate until the engine is started again.
False triggering
Higher amounts of methanol/ethanol (or other additives) than the engine is equipped to handle may trigger the MIL (see E85). These burn differently from gasoline, and the EFI system may mistakenly interpret the oxygen sensor's readings as being incorrect. Oxygenated gasoline can cause this false triggering in early EFI systems.[citation needed]
See also
- OBD-II PIDs ("Parameter IDs")
References
- ^ 1980s and 1990s Ford F-Series trucks had an optional "redundant engine light", a second engine light alongside the check engine light, which would only light under severe conditions. As the name suggests, its purpose was redundancy in case the primary MIL failed.
- ^ "Check Engine Light".
- ^ On vehicles equipped with OBD-II
- ^ "Diagnose service engine soon light fix with this professional car diagnostic tool". Key Smiths. April 11, 2018. Retrieved April 11, 2018.
- ^ https://books.google.com/books?id=q8_vHlaJHVwC&pg=PA200&dq=Malfunction+indicator+light+OBD&hl=en&ei=h4j-TNSEFoiDOpaCvc4M&sa=X&oi=book_result&ct=result&resnum=1&ved=0CC0Q6AEwAA#v=onepage&q=Malfunction%20indicator%20light%20OBD&f=false Code of Federal Regulations CFR 40 ar{Part 86, retrieved 2010 Dec 7
- ^ "Engine trouble". Archived from the original on October 28, 2016. Retrieved October 27, 2016.
- ^ "Why Does My Car Stall?". Desert Oasis Auto Repair. December 2015.
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