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 or problem with the vehicle ranging from minor (such as a loose gas cap) to serious (worn spark plugs, engine problems or a faulty oil valve, etc.). Found on the instrument panel of most automobiles, it usually bears the legend engine,[1] check engine, service engine soon, maintenance required, emiss 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 repairable fault, but service on the vehicle is strongly recommended as soon as possible to prevent future damage) and flashing (indicating a severe fault and an emergency that makes the vehicle unsafe to drive and it is strongly recommended that the vehicle gets mechanical attention straight away). 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 or fault in the engine.[4]
In the United States, specific functions are required of the MIL by EPA regulations.[5]
History
Some older vehicles had a single indicator labeled "trouble" or "engine"; this was not an MIL, but an "idiot 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.
The MIL appeared in the early 80s along with computerized engine controls. Even the earliest systems, such as General Motors' CCC (computer command control) 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, such as Honda, retained this feature even after OBDII.
The MIL is commonly referred to today as the "check engine light" or the "service engine soon light".[6][7][8]
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.
If you're experiencing a check engine light or antilock brake (ABS) warning light while on the road, it's important to address these issues promptly. Here's how you can use Wikipedia and other resources to understand these warnings: Check Engine Light Understanding the Check Engine Light
The check engine light is part of your vehicle's onboard diagnostics system. It can indicate a range of issues, from minor problems like a loose gas cap to more serious engine or emissions system issues. Search for "Check Engine Light" on Wikipedia to get a general understanding of what it means, common causes, and potential solutions. Wikipedia can provide background information on how the onboard diagnostics system works and what different codes might mean.
Immediate Steps Ensure your gas cap is tightly secured, as this is a common cause for the light to come on.
If the light is flashing, it indicates a more serious problem that requires immediate attention. Reduce speed and avoid heavy acceleration.
Further Diagnosis
Consider using an OBD-II scanner to read diagnostic trouble codes (DTCs) from your vehicle's computer. These codes can help identify the specific issue. Visit a mechanic or auto repair shop for a professional diagnosis if you're unsure about handling it yourself.
Antilock Brake System (ABS) Light Understanding the ABS Light
The ABS light indicates a problem with the antilock braking system, which helps prevent wheel lockup Antilock Braking System". to learn about how ABS works, its components, and common issues that trigger the warning light.
While the ABS light is on, your regular brakes will still function, but the antilock feature may not work. Drive cautiously and allow extra stopping distance. Avoid sudden stops and maintain a safe following distance from other vehicles.
Check the brake fluid level, as low fluid can sometimes trigger the ABS light. Have a professional inspect the ABS system to diagnose and fix any issues.
By using Wikipedia and other reliable sources, you can gain a better understanding of these warning lights and take appropriate action. However, always prioritize safety and seek professional assistance when needed.
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")
- Tell-tale (automotive)
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.
- ^ Register, Office of the Federal. Code of Federal Regulations, Title 40, Protection of Environment, PT. PT. 85-86 (SEC. 86.599-99), Revised as of July 1, 2010. Government Printing Office. ISBN 978-0-16-086040-9.
- ^ "How do the engines breathe in diesel submarines?". How Stuff Works. 24 July 2006. Retrieved October 27, 2016.
- ^ "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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