It can be frustrating when your car engine refuses to start, especially if it happens right after you’ve used an OBD2 scanner to check for potential issues. While the OBD2 scanner itself isn’t typically the cause of a no-start condition, the timing can lead to confusion. Let’s clarify how OBD2 scanners work and explore the common culprits behind an engine that won’t start, even after using a diagnostic tool.
OBD2 scanners are designed to read diagnostic trouble codes (DTCs) from your car’s Powertrain Control Module (PCM). They are essentially readers, not controllers. They retrieve information about your vehicle’s health but do not directly control engine functions like starting. The PCM is responsible for managing crucial systems, including the fuel pump and starter relay. For the engine to start, several components need to work in harmony.
One key component is the fuel pump relay. When you turn the ignition to the “Run” position, the PCM energizes the fuel pump relay for a few seconds. This action primes the fuel system by running the fuel pump and pressurizing the fuel rail, preparing the injectors for engine start. If the PCM or fuel pump relay is malfunctioning, the engine might not receive fuel, preventing it from starting.
Another critical system is the starter motor circuit. When you turn the key to the “Crank” position, power flows through the starter circuit. This involves the Neutral Safety Switch (for automatic transmissions) or Clutch Safety Switch (for manual transmissions), the starter solenoid relay, and finally, the starter motor itself. If there’s an issue in this circuit, such as a faulty safety switch, a bad starter solenoid relay, or a failing starter motor, the engine won’t crank or start. Simple issues like corroded or loose battery cables can also prevent the starter motor from receiving enough power, as the starter draws a significant amount of current. A common problem in some vehicles is also worn starter solenoid contacts, which can hinder the starter’s operation.
In summary, if your car won’t start after using an OBD2 scanner, it’s unlikely the scanner is at fault. Instead, focus on diagnosing common starting problems related to the fuel system, starter system, and basic electrical connections. Check your battery cables for tightness and corrosion, listen for the fuel pump priming when you turn the key to “Run,” and investigate the starter motor’s operation when you try to crank the engine. These steps will help you pinpoint the real reason why your engine is not starting.
