What Could Be the Reason When a Car Fails to Start Despite Everything Appearing Normal?
3 Answers
There are two scenarios when a car fails to start: Battery Depletion: When the car battery is depleted, the vehicle may fail to start. Several factors can lead to battery depletion, such as insufficient battery water, battery malfunction, or prolonged use of the air conditioning. If the car doesn't start, the first step is to check whether the battery is the issue and identify the specific problem before sending it to a 4S shop for repair. Extremely Low Temperatures: During cold winter weather, cars often have difficulty starting. This is because, in low-temperature environments, the viscosity and rotation speed of the car's engine oil decrease, leading to reduced ignition energy from the battery and decreased molecular activity. As a result, flammable gases cannot form, making it difficult for the car to start.
I've encountered this situation many times while repairing cars over the years. The car looks perfectly normal on the outside but won't start, and there are actually many possibilities hidden beneath the surface. The most common issue is with the battery. It may appear to power the lights and horn, but starting requires a large current, and there might be a minor internal short circuit or oxidized terminals causing poor contact. Another possibility is a faulty starter solenoid switch, where you can hear a clicking sound when trying to start, but the engine doesn't turn over. In terms of the fuel system, insufficient fuel pressure from the fuel pump or clogged fuel injectors can also prevent the car from starting. Recently, I worked on a car where half of the fuel line was crushed, blocking fuel flow. Additionally, sensor failures, such as a problematic crankshaft position sensor, can prevent the engine computer from receiving the ignition signal. In such cases, it's best not to keep trying forcefully, as this can easily burn out the starter. The most reliable approach is to take it directly to a repair shop and use a diagnostic tool to read the fault codes.
Last week my car had this exact issue - dashboard lights all on, horn working, but turning the key got no response. After struggling for hours, found out the transponder chip in the key got damp and failed, triggering the immobilizer to lock the engine. My friend's case was even crazier - his DIY dashcam installation short-circuited the cigarette lighter fuse, which unexpectedly controlled the fuel pump relay circuit. Actually beyond anti-theft issues, incomplete P-gear engagement or faulty brake switch contacts can also prevent ignition. Once I panicked rushing to work only to realize I forgot to press the brake while turning the key. Even with seemingly full battery charge, insufficient cold cranking amps will still cause failure - jumper cables easily solve this. Now I always keep a portable jump starter in the car to avoid roadside strandings.
