Using an OBD2 scan tool to check your car’s health is usually a breeze. You plug it in, and it quickly tells you what’s wrong, right? But sometimes, you might face a frustrating “No Communication” error. This can be confusing and leave you wondering why your OBD scanner can’t read the error codes.
This article will explore common reasons behind communication errors between your OBD2 scanner and your vehicle. We’ll guide you through troubleshooting steps to get your scanner working and reading those crucial error codes. Understanding why your Obd Scanner Reads Error is the first step to fixing the problem and getting your car back in top shape.
Communication issues can stem from various factors, including the ignition key position, voltage problems in the connector, incorrect communication protocols, a frozen ECM, missing or corrupted data, or outdated ECM software that your scan tool doesn’t recognize. Let’s delve deeper into these potential causes.
OBD Scanner Compatibility Issues
While most OBD code readers are designed to work with vehicles using standardized OBDII protocols – essentially covering engine and emission management systems in OBD2 compatible cars – compatibility can still be a hurdle. One common reason why your OBD scanner reads error or fails to connect is that your car might use a non-standard OBD protocol. Older protocols like ALDL, MOBD, MUTT, or OBD1 are manufacturer-specific and require specialized scan tools.
Alt: Checking OBD2 scanner compatibility with vehicle’s diagnostic port to ensure proper communication.
If you’re working with a wider range of vehicles, especially older models, a professional multi-system diagnostic scanner with OBD1 and OBD2 compatibility is essential. These advanced scanners come equipped with software capable of interpreting diverse protocols, ensuring they can effectively OBD scanner reads error codes across different makes and models.
Ignition Key Position: Is It in the ‘Run’ Position?
A simple oversight can often be the culprit when your OBD scanner reads error: the ignition key position. Most OBDII scan tools need the ignition to be in the ‘Run’ position, or the engine running, to establish a connection. Furthermore, modern vehicles have complex electronic systems that take time to boot up.
It’s a good practice to wait a few seconds after turning the ignition to ‘Run’ before plugging in your scanner. Wait until all dashboard lights have settled, and any chimes have finished. Trying to connect before the system is fully booted can lead to communication errors, and your OBD scanner reads error message instead of vehicle data.
Voltage Problems at the OBDII Connector
The OBDII connector is designed to supply power to the scan tool. By specification, pin 16 must provide 12-volt power, and pins 4 and 5 should be ground. Scan tools rely on this power supply to function correctly. If there’s a voltage issue, your OBD scanner reads error or might not even power on properly.
Alt: Using a voltmeter to check for 12V power at pin 16 of the OBD2 connector, a crucial step in diagnosing OBD scanner communication errors.
Here’s how to check for voltage issues:
- Turn the ignition to the ‘Run’ position.
- Use a voltmeter set to DC voltage.
- Place the red (positive) lead on pin 16 and the black (negative) lead on pin 4 or 5.
The voltmeter should read close to 12V DC. If the reading is significantly below 11 volts, it could be causing connection problems. In this case, inspect your car’s battery and charging system. Low battery voltage can definitely contribute to why your OBD scanner reads error.
No Voltage Reading? Check Fuses!
If you get no voltage reading at all, a blown fuse is the most likely culprit. The OBDII connector often shares a fuse with the accessory power circuit. Consult your car’s owner’s manual to locate the fuse panel diagram. Check for blown fuses, and if you find one, replace it and re-check the voltage at the OBDII connector. This simple fix can often resolve why your OBD scanner reads error.
ECM Communication Hang-Ups
Sometimes, the Engine Control Module (ECM) can get stuck in a ‘hung’ state. In this situation, it might be functioning enough for the car to run, but it fails to communicate externally. You might experience this as your OBD scanner reads error despite the car seeming to operate normally.
Rebooting the ECM can often resolve this issue. Here’s how to do it:
- Disconnect both battery cables (negative first).
- Press the brake pedal for a few seconds. This discharges any residual power in the system’s capacitors.
- Reconnect the battery cables (positive first).
Alt: Disconnecting car battery terminals to reboot the ECM, a potential fix when OBD scanner reads error due to communication issues.
After reconnecting the battery, the ECM will reboot. This process can often clear up communication issues, allowing your OBD scanner reads error codes correctly afterwards. Always consult your vehicle’s owner’s manual for specific instructions before disconnecting the battery, as some vehicles may require specific procedures to avoid issues with other systems.
Missing or Invalid Data: PID Issues
When you connect an OBD scanner, it queries the ECM for valid Parameter IDs (PIDs) relevant to your vehicle. Some scanners might remember the PIDs from the last vehicle they connected to. If these PIDs don’t match the current vehicle, you might encounter issues where your OBD scanner reads error or shows inaccurate data. Some PIDs might even show up as “not available.”
To fix this, most scan tools have a function to re-query for PIDs. This process can take a minute or two, depending on the vehicle. Once completed, the PID list should accurately match your vehicle, and the data should be correct. Some scanners use the vehicle’s VIN to automatically determine valid PIDs.
As a best practice, always initiate a PID scan to ensure your tool is reporting accurate data directly from your ECM. Spending a minute to query PIDs is a worthwhile step to ensure your OBD scanner reads error codes and live data correctly.
Conclusion: Beyond the Scan Tool Error
Just like computers, vehicle ECM software can sometimes have glitches that affect communication. Many car owners don’t realize that sometimes, when an OBD scanner reads error, further in-depth diagnosis might be necessary before you can effectively use the scan tool to read and clear fault codes or perform service resets. A diagnostic scan tool is not always a magic bullet.
The points discussed above are common reasons why your OBD scanner reads error, but they are not exhaustive. Effectively using diagnostic scan tools requires a good understanding of vehicle technology. Choosing the right diagnostic equipment and suppliers is also crucial. Opt for reputable local suppliers known for their customer support and expertise. They can provide valuable assistance with troubleshooting and answer any questions you might have, ensuring you can effectively use your OBD scanner reads error codes and maintain your vehicle.
