Experiencing a red light on your BAFX OBD2 reader but struggling to establish a connection with your Mazda Miata can be frustrating. Many Miata owners, especially those with the ’99 NB model, encounter this issue. You’re not alone if your BAFX OBD2 adapter shows a red light when plugged into your Miata, yet apps like Torque or Car Gauge Lite fail to communicate with the vehicle’s ECU (Engine Control Unit). This guide will explore why this might be happening and provide troubleshooting steps to get your OBD2 reader working.
It’s understandable to be concerned, particularly when the adapter functions perfectly on another vehicle, like a Honda Civic. Let’s break down the common questions and issues related to BAFX OBD2 readers and Miata NBs.
Understanding the OBD2 Port Location on Your ’99 Miata
One common point of confusion is the location of the OBD2 port itself. You mentioned finding a port under the fuse box cover to the left of the driver’s knee. While there are electrical components in that area, the actual OBD2 port on a 1999 Mazda Miata (NB) is typically located lower in the driver’s side footwell.
When your mechanic accessed the OBD-II codes without removing the fuse box cover, they were likely using the correct port. Reaching further down and towards the center console in the footwell, you should find the OBD2 connector. This location is standard for the NB Miata and is designed for diagnostic access.
Using the port under the fuse box would indeed be inconvenient and is likely not the intended OBD2 port for diagnostics. Double-check the footwell area to locate the correct 16-pin OBD2 connector.
Protocol Compatibility and Your BAFX OBD2 Reader
OBD2 protocols are standardized, but sometimes older vehicles, or specific models, can be a bit particular. While the ’99 Miata is OBD2 compliant, there’s a possibility that the auto-protocol detection of your BAFX reader is not correctly identifying the protocol used by your Miata’s ECU.
The original post mentioned trying “Auto” protocol selection. While “Auto” should work, it might be worth manually specifying a protocol within your Torque app or Car Gauge Lite. Common OBD2 protocols include:
- ISO 9141-2: This is a protocol commonly used in many Japanese and European vehicles from the late 90s and early 2000s, and it’s a likely candidate for your ’99 Miata.
- ISO 14230-4 (KWP2000): Another protocol that could be relevant.
Consult your app settings to see if you can manually select an OBD2 protocol. Experiment with ISO 9141-2 first, as it’s frequently used in vehicles of that era. Trying a manual protocol selection can sometimes bypass issues with auto-detection.
BAFX OBD2 Reader Compatibility with NB Miatas
While BAFX OBD2 readers are generally well-regarded and compatible with a wide range of vehicles, there’s always a chance of specific compatibility issues. It’s less about the brand being “picky” and more about the nuances of OBD2 implementation across different car models and years.
The fact that your BAFX reader works on a ’98 Civic is a good sign the adapter itself is functional. However, it doesn’t guarantee compatibility with every OBD2 vehicle.
Here’s what to consider regarding compatibility and troubleshooting:
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Power and the Red Light: The red light on your BAFX adapter indicates it’s receiving power from the OBD2 port. This is a positive sign, suggesting the port itself is functioning and providing power. However, power alone doesn’t guarantee data communication.
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App and Adapter Pairing: You’ve successfully paired your Android device with the BAFX adapter via Bluetooth. This step seems to be correctly done. Double-check the pairing code (1234 is common, but confirm if specified).
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App Settings and Configuration: Within Torque or Car Gauge Lite, ensure you’ve selected the correct Bluetooth device (your BAFX adapter). Sometimes, apps might default to a different connection type or device.
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ECU Response: The “No response from vehicle ECU” message is the key symptom. This means the app and adapter are likely communicating, but they are not receiving data back from the Miata’s computer.
Troubleshooting Steps for No ECU Response
If you’ve confirmed the correct OBD2 port location and tried manual protocol selection, here are further troubleshooting steps:
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Restart Everything: Turn off your car, unplug the OBD2 reader, close the Torque/Car Gauge Lite app completely, and restart your Android device. Then, plug the reader back in, start the car (or just turn the ignition to “ON”), reopen the app, and try connecting again. A simple restart can sometimes resolve temporary glitches.
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Try a Different OBD2 App: While Torque and Car Gauge Lite are popular, try another OBD2 app from the Google Play Store. There are many free and paid options. A different app might have slightly different communication methods or protocol handling that works better with your Miata.
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Verify OBD2 Port Power: Although the red light suggests power, you can use a simple OBD2 port tester or a multimeter to definitively check for power at the OBD2 port pins. (This is more advanced and usually not needed if the red light is on).
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Check Miata Fuses: Consult your Miata owner’s manual and check the fuses related to the ECU or diagnostic system. A blown fuse could potentially prevent OBD2 communication, although it might cause other symptoms as well.
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Test on Another OBD2 Car (if possible): While you tested on the Civic, if you have access to another OBD2 compliant vehicle (ideally from a similar era, if possible), try the BAFX reader on that car to further isolate if the issue is specific to the Miata.
When to Consider a Different OBD2 Reader
If you’ve exhausted these troubleshooting steps and still cannot connect, it might be worth considering trying a different OBD2 reader. While the BAFX is generally reliable, compatibility issues can occur.
Before returning your BAFX adapter, ensure you’ve thoroughly investigated all other potential causes. If, after extensive troubleshooting, you suspect the reader itself is the issue, researching OBD2 readers specifically known to be compatible with Mazda Miatas (NB models) could be the next step. Online Miata forums and communities can be valuable resources for recommendations on OBD2 readers that work well with NBs.
In conclusion, a red light on your BAFX OBD2 reader indicates power, but “no response from ECU” points to a communication issue. By verifying the OBD2 port location, exploring protocol settings, and systematically troubleshooting, you can often resolve these connection problems and get your OBD2 reader working with your ’99 Miata. If issues persist, considering a different reader might be necessary, but thorough troubleshooting should be the first step.
