The frustration of turning your key in the ignition or pressing the start button only to be met with silence is something every car owner dreads. In today’s tech-driven world, many car owners reach for an onboard diagnostic (OBD2) scanner in these situations, hoping it holds the key to understanding why their car won’t turn over. But how effective is a car scanner when your vehicle refuses to start? Understanding the capabilities and limitations of these devices is crucial to effectively diagnosing your car’s starting problems.
The straightforward answer is: yes, a car scanner, specifically an OBD2 scanner, can still be a valuable tool even if your car won’t start. As long as your car’s battery retains enough charge to power the electronic systems, an OBD2 scanner can connect, retrieve diagnostic trouble codes (DTCs), and provide access to valuable data streams. However, the extent to which it can help diagnose a no-start issue depends on the underlying problem.
It’s important to note that if the car’s battery is completely dead, an OBD2 scanner will likely not function because the car’s electronic control module (ECM) and other systems won’t receive power. Furthermore, OBD2 scanners are most effective at identifying issues within the car’s electronic systems. They are less helpful for diagnosing purely mechanical failures, such as a completely failed starter motor or a fuel pump that has stopped working due to mechanical wear. Instead, these scanners excel at reading electronic data related to engine performance, emissions controls, and the vehicle’s electrical system.
Common Reasons Why a Car Won’t Turn Over and How a Scanner Can Help
Knowing the common culprits behind a car that won’t turn over is the first step in deciding whether a car scanner can assist you or if other diagnostic methods are needed. Here are some of the primary reasons:
Battery Issues:
- Dead or Weak Battery: A dead battery is a prime suspect when your car is unresponsive. No power means no function for any electronic systems, including the OBD2 port. A weak battery might allow some lights to flicker or produce a clicking sound when you try to start, but still lack the amperage to crank the engine. In these battery-related scenarios, while the scanner itself might not be able to connect if the battery is completely drained, addressing the battery issue is the first step before further diagnosis.
- Corroded or Loose Battery Terminals: Even with a good battery, corroded or loose terminals can impede power flow, leading to start-up failures. These issues are less likely to be directly flagged by an OBD2 scanner but are crucial to check as part of basic troubleshooting.
Starter Motor Failure:
The starter motor is the workhorse responsible for cranking your engine. If it fails, you’ll likely hear nothing or just a single click when attempting to start. Unfortunately, starter motor failures are often mechanical and won’t typically trigger OBD2 codes. A car scanner is generally not designed to diagnose a mechanically failed starter.
Fuel Delivery Issues:
- Fuel Pump Problems or Blockages: A faulty fuel pump, clogged fuel filter, or blocked fuel lines can starve the engine of fuel, preventing it from starting. While a mechanical fuel pump failure might not set a specific OBD2 code, related sensor issues, such as low fuel pressure readings, could be detected by a scanner.
- Empty Fuel Tank or Contaminated Fuel: It sounds obvious, but running out of gas is a surprisingly common reason for a no-start. Similarly, contaminated or bad fuel can also prevent combustion. A car scanner won’t tell you if you’re out of gas, but in some advanced systems, fuel quality issues might indirectly affect sensor readings that a scanner could pick up.
Ignition System Issues:
Problems within the ignition system, such as a failing ignition coil, distributor (in older vehicles), or worn spark plugs, can prevent the engine from firing up. Ignition system malfunctions can sometimes trigger OBD2 codes, particularly those related to misfires or crankshaft/camshaft position sensor discrepancies, which the scanner can identify.
Sensor Failures:
Modern engines rely heavily on sensors to manage timing and fuel delivery. Critical sensors like the camshaft position sensor (CMP) or crankshaft position sensor (CKP) are essential for starting. If these sensors fail, the ECM might prevent the engine from starting to avoid potential damage. This is where a car scanner becomes highly useful. Sensor failures often generate specific DTCs that an OBD2 scanner can readily detect, guiding you to the source of the problem.
Using a Car Scanner to Diagnose a No-Start Condition
If your car won’t turn over, using a car scanner to check why car won’t turn over, like the Foxwell NT726 or similar models, can significantly streamline the diagnostic process. These scanners offer features like system-wide diagnostics, live data streaming, and comprehensive code reading capabilities.
Before connecting your scanner, ensure your car battery has at least some charge. Most OBD2 scanners draw power from the car’s battery. If the battery is completely dead, you might need to jump-start the car or use a battery maintainer to get some power before the scanner can operate.
Here’s a step-by-step guide to using a car scanner for a no-start issue:
- Locate the OBD2 Port: Typically, the OBD2 port is located under the dashboard on the driver’s side. Consult your vehicle’s owner’s manual if you are unsure of its exact location.
- Connect the Scanner: Plug your Foxwell NT726 or chosen scanner into the OBD2 port securely.
- Turn Ignition to “ON” (Accessory) Position: Turn your ignition key to the “ON” position or press the start button to the accessory mode. This powers up the car’s electronics without engaging the starter.
- Power On the Scanner: The scanner should power on automatically. Follow the scanner’s prompts to connect to the vehicle.
- Read Trouble Codes: Navigate to the “Read Codes” or “Diagnostic Codes” menu option on your scanner. The scanner will communicate with the car’s computer and display any stored DTCs. Note down these codes and their descriptions. The Foxwell NT726 and similar scanners often provide detailed explanations of the codes, helping you understand potential problem areas like ignition, fuel, or emissions systems. Sensor-related issues, such as problems with the crankshaft position sensor, will also typically be flagged with specific codes.
- Analyze Live Data: Utilize the “Live Data” or “Data Stream” function on your scanner. This feature allows you to monitor real-time data from various sensors and systems. For a no-start condition, relevant parameters to monitor include fuel pressure, RPM while cranking, throttle position, and ignition timing. For example, if you suspect a fuel delivery issue, check the fuel pressure reading while attempting to start the car. Abnormally low or no fuel pressure could indicate a fuel pump problem.
- Clear Codes and Re-scan (After Repairs): Once you have diagnosed and addressed the issue, use the scanner’s “Clear Codes” function to erase the stored DTCs. This will turn off the check engine light if it was illuminated due to the problem. After clearing codes and attempting to start the car again, re-scan for codes to see if any new codes appear or if the original codes return. This can help confirm if the repair was successful or if there are still underlying issues.
Alternative Diagnostic Methods When You Don’t Have a Car Scanner
Even without a car scanner, you can employ several methods to diagnose why your car won’t start:
- Check Battery Voltage with a Multimeter: A multimeter is an essential tool for basic car diagnostics. A healthy battery at rest should read around 12.6 volts. If it’s significantly lower, the battery might be the issue. Try jump-starting the car. If it starts with a jump, the battery or charging system is likely the problem.
- Inspect Battery Connections: Visually examine the battery terminals for corrosion. Clean them with a wire brush and ensure the connections are tight.
- Listen for the Fuel Pump: When you turn the ignition to the “ON” position (before starting), you should hear a brief whirring sound from the fuel pump, usually coming from near the fuel tank. No sound could indicate a fuel pump failure.
- Test for Starter Motor Power: Use a test light or multimeter to check if the starter motor is receiving power when you turn the key to the start position. If power is reaching the starter but it’s not engaging, the starter motor itself might be faulty.
- Check for Spark: If you suspect an ignition problem, you can use a spark plug tester to see if the spark plugs are firing. No spark can point to issues with the ignition coil, distributor (if applicable), or other ignition components.
Preventive Maintenance to Minimize Starting Problems
Regular car maintenance is key to preventing many starting issues:
- Maintain Battery Health: Regularly inspect your battery terminals for corrosion and clean them as needed. Have your battery tested periodically, especially as it ages (typically every 3-5 years). Consider proactive battery replacement to avoid unexpected failures.
- Use Quality Fuel and Replace Fuel Filter: Using good quality fuel and adhering to the recommended fuel filter replacement intervals helps maintain the fuel system and prevents blockages.
- Maintain the Ignition System: Follow your vehicle’s maintenance schedule for spark plug replacement. Inspect ignition wires and distributor caps (if applicable) for wear and tear.
- Regular Sensor Checks: While you can’t directly “check” sensors without diagnostic tools, be aware of symptoms like rough idling or misfires, which could indicate sensor issues. Address these promptly to prevent more serious problems.
Conclusion
A car scanner is indeed a valuable tool when your car won’t turn over, particularly for diagnosing issues within the electronic systems. Scanners like the Foxwell NT726 can effectively identify problems related to sensors, ignition, and emissions by reading diagnostic trouble codes and providing live data. However, it’s crucial to understand their limitations. OBD2 scanners are less effective at pinpointing mechanical failures like starter motors or purely mechanical fuel pump failures.
For a comprehensive diagnosis of a no-start condition, especially when a car scanner doesn’t provide clear answers, combining scanner diagnostics with traditional troubleshooting methods like checking battery voltage, fuel delivery, and spark is essential. And when you’re unsure or lack the tools and expertise, seeking professional assistance from a qualified mechanic is always the best course of action. They have access to advanced diagnostic equipment and the experience to tackle complex no-start issues efficiently.
FAQs
Can I use a code reader if my car won’t start?
Yes, you can typically use a code reader (OBD2 scanner) even if your car won’t start, as long as the car’s battery has enough charge to power the electronic systems.
Do you have to start the car to use the OBD2 scanner?
No, you do not need to start the car. Simply turning the ignition to the “ON” or “Accessory” position is usually sufficient to power up the car’s computer and allow the OBD2 scanner to access vehicle data.
Can an OBD scanner detect starter problems?
Not directly. An OBD scanner is designed to read electronic diagnostic codes and is not typically capable of directly detecting mechanical issues like a faulty starter motor. However, in some cases, related electrical problems within the starting circuit might indirectly trigger codes that could offer clues.
