Why does the engine self-check light not come on and the car fail to start?

[AthenaLynn]

When the engine self-check light does not come on and the car fails to start, this situation is generally caused by a loose connection in the engine power circuit or corrosion in the ECU wiring due to water ingress. It is recommended to seek further inspection at a professional auto repair shop. When the car engine is not functioning properly and the self-diagnostic system does not output any fault codes, it is especially necessary to rely on the inspection and judgment of the operator to determine the nature and location of the fault. Reasons for the self-check light to come on: 1. Sensor issues: Sensors include those for coolant temperature, crankshaft position, air flow, intake air temperature, and oxygen. When these sensors are damaged, have poor contact, or signal interruption, the car's ECU cannot accurately obtain engine data, which will cause the engine self-check light to come on. 2. Maintenance issues: Poor engine maintenance is the most common cause of the engine self-check light coming on. Vehicles have a certain maintenance cycle, and if the owner does not perform maintenance on schedule, coupled with poor driving habits, it will increase the burden on the engine's operation. 3. Oil quality issues: Oil quality includes fuel and engine oil. If the owner does not add the appropriate oil as required, it will cause engine wear over time.

[PhoebeFitz]

Having run this auto repair shop for so many years, I often encounter situations where the engine check light doesn't come on and the car won't start. This is mostly due to power system issues. A completely dead battery or extremely low voltage is the most common cause - since both the dashboard lights and ECU rely on battery power, without electricity none of the systems can activate, naturally resulting in no lights and failure to start the engine. Another possibility is a blown main fuse - when critical fuses in the engine compartment fuse box burn out, the entire circuit gets cut off, and the computer can't detect problems so the warning light won't illuminate. Loose or corroded wiring connections may also cause poor contact. Occasionally, it could be a faulty ignition switch affecting signal transmission. Never force-start the engine as it may damage components. I recommend first checking the battery - use a multimeter to test if voltage drops below 12 volts. If that's fine, inspect the fuses and replace any blown ones with new ones. If you can't figure it out, call a tow truck to take it to a professional shop where they have complete equipment to diagnose deeper issues. Regular maintenance and periodic battery health checks can help prevent such troubles.

[OGeorge]

Last time my car suddenly had all dashboard lights go out in the garage, and turning the key got no response - I panicked badly. A friend told me it was most likely due to a completely dead battery from aging, especially prone in winter. The self-check lights only illuminate when the computer detects normal systems, but with no power at all, of course the lights wouldn't come on and the engine wouldn't start. Battery issues are the most common cause, particularly when the car hasn't been driven for too long. You can try turning on the headlights - if they don't light up, it basically confirms no power, and you just need to charge or jump-start it. Blown fuses are another potential cause, like when heavy rain causes wiring short circuits that burn out fuses, requiring inspection and replacement in the fuse box. Never attempt DIY repairs - calling roadside assistance is the most worry-free solution. Since then, I've tested the battery every year before winter and replaced it when lifespan ends, preventing similar headaches. Developing good habits saves a lot of trouble.

[AdrianRose]

As a car enthusiast, I find it quite interesting when the engine self-check light doesn't illuminate, causing the car to fail to start. This light is activated by the ECU computer after powering up and performing system checks. If it doesn't light up, it means the ECU hasn't started at all, possibly due to a depleted battery, relay failure, or disconnected power lines. Since the ECU controls fuel injection and spark, no power naturally leads to engine start failure. When troubleshooting, start with the battery to check if oxidized or loose terminals are affecting power supply. Blown main fuses in the fuse box are also common, often caused by excessive short-circuit current. While faulty sensors like the crankshaft position sensor can make starting difficult, they won't prevent the light from illuminating, so they can be ruled out. Understanding these mechanisms helps solve problems quickly: keep a power bank for emergency charging, test voltage first, then inspect the fuse panel if normal. Regular maintenance of the electrical system, such as cleaning terminals, can prevent most issues.