It can be frustrating when your car refuses to start right after you’ve used an OBD-II scanner. Many drivers might understandably assume the scanner caused the problem. However, it’s crucial to understand that OBD-II scanners themselves do not control or alter your car’s engine or starting system. Their primary function is to read and display Diagnostic Trouble Codes (DTCs) from your car’s Powertrain Control Module (PCM).
The PCM is the brain of your car’s engine management system, and it’s responsible for various functions, including the fuel pump relay and fuel gauge operation. When you turn your ignition to the “Run” position, the PCM activates the fuel pump relay for a few seconds. This pre-primes the fuel system, ensuring there’s pressure in the fuel rail and injectors for a smooth startup. The PCM needs a stable power supply to perform these functions correctly.
When you crank the ignition to start the car, power from the battery flows through the starter circuit. This circuit typically involves a Neutral Safety Switch (for automatic transmissions) or a Clutch Safety Switch (for manual transmissions), and a Starter Solenoid Relay. If all safety switches are engaged and the relay is functioning, power is then sent to the Starter Solenoid coil, which in turn engages the Starter Motor to crank the engine.
So, if your car doesn’t start after using an OBD scanner, the scanner is likely not the direct cause. Instead, consider these more probable reasons:
- Pre-existing Condition Highlighted: Using the OBD scanner may have simply been coincidental timing. The underlying issue preventing your car from starting was likely already present. The process of scanning might have drawn a little extra power, or simply brought your attention to a problem that was about to surface.
- Battery Issues: Scanning can put a slight drain on the battery, especially if the ignition is left in the “ON” position for an extended period during scanning. If your battery is already weak, this minor drain could be enough to prevent starting. Low voltage can affect the PCM’s ability to properly energize the fuel pump relay or engage the starter.
- Loose or Corroded Battery Cables: A common culprit for starting problems is poor battery cable connections. Ensure your battery terminals and cable ends are clean and tightly secured. The starter motor requires a significant amount of current, and resistance from corroded or loose connections can hinder its operation.
- Starter Solenoid Problems: Another frequent issue, particularly in some vehicle models, is worn starter solenoid contacts. If you hear a clicking sound when you try to start the car, but the engine doesn’t crank, this could indicate a faulty starter solenoid.
In conclusion, while it might seem like your OBD scanner is to blame when your car won’t start afterward, it’s far more likely that the scanner usage coincided with an existing or developing issue in your car’s starting system. Focus on diagnosing the common starting problems outlined above, and remember the OBD scanner is a diagnostic tool, not a component that directly impacts your car’s ability to start.
