OBD-II Adapters and Apps for the ND MX-5

An OBD-II adapter plus a phone app turns the ND’s diagnostic port into a live gauge cluster: coolant temp, intake air temp, throttle position, fuel level, and fault codes, all on your phone. The ND’s port is under the dash on the driver’s side, left of the steering column, on every 2016+ MX-5.

This is a different job from FORScan, which configures body and infotainment modules and needs a switchable MS-CAN adapter (see the FORScan adapter buying guide). One adapter can do both, but most people buy for one purpose. Start by deciding which you’re doing.

What you want to do	What you need
Live gauges and fault codes on your phone	Any decent OBD adapter + app (this page)
Read/clear a check-engine light	Any OBD adapter + app
Configure modules (FORScan)	Switchable MS-CAN adapter — adapter guide
Lap timing with engine data overlaid	OBD adapter + RaceChrono, or a dedicated logger — data loggers compared

Which adapter to buy

OBDLink MX+ (Bluetooth) — the one to get

The MX+ uses ScanTool’s STN chip rather than a clone ELM327, and it shows: faster polling, a stable connection, and proper multi-protocol support. It’s also the adapter that can switch to MS-CAN in software, so the same unit handles FORScan. If you might ever do module coding, this is the dual-purpose buy.

Spec	Detail
Connection	Bluetooth (Classic + BLE)
Protocols	All OBD-II protocols including CAN; MS-CAN software-switchable
App support	Car Scanner, OBD Fusion, Torque, FORScan, RaceChrono
Platform	iOS, Android, Windows
Price	~$140

Veepeak OBDCheck BLE+ — the budget monitor

Genuine, reliable, and cheap. It reads standard OBD-II fine and is a solid choice if all you want is gauges and code reading. It cannot reach MS-CAN, so it will not do FORScan body-module work.

Spec	Detail
Connection	Bluetooth Low Energy
Protocols	Standard OBD-II only (no MS-CAN)
App support	Car Scanner, OBD Fusion, Torque
Platform	iOS, Android
Price	~$35–45

Adapters to skip

The $10–15 Bluetooth adapters on Amazon and eBay are almost always counterfeit ELM327 chips with a faked version string. They connect, work for a few minutes, then drop, poll slowly, and report stale or wrong values. The frustration isn’t worth the savings.

Adapter type	Problem
Generic ELM327 “v1.5” clones	Counterfeit chip, slow polling, dropped connections
Generic ELM327 “v2.1” Bluetooth	Faked version number, unstable
Generic WiFi OBD dongles	Slow, and they hijack the phone’s WiFi radio
”All-in-one” no-name dongles	Random firmware, no support

Apps

Pick by platform first.

Car Scanner (iOS / Android)

Modern interface, sensible default gauge layouts, reliable connection. Free with a one-time pro unlock (~$5). The easiest starting point on either platform, and the one most ND owners settle on for daily monitoring.

OBD Fusion (iOS)

The best iOS OBD app: custom PID definitions, data logging to CSV, clean gauges. ~$10. If you’re on iPhone and want to log enhanced Mazda signals, this is the pick.

Torque Pro (Android)

The long-time Android standard, ~$5. Highly customizable dashboards, broad PID support, a plugin ecosystem, and community PID packs that add Mazda-specific signals. The UI is dated but it does more than anything else on Android.

RaceChrono (iOS / Android)

Track-focused: it overlays OBD data onto a GPS lap trace for timing and analysis. Free tier plus a pro unlock (~$10). Overkill for street monitoring, but the right tool if you want engine data tied to a lap. For how it stacks up against dedicated boxes, see data loggers compared.

What you can actually read

Standard OBD-II PIDs are available on any working adapter and cover the signals most owners care about:

PID	Signal	Typical rate
0x0C	Engine RPM	~10 Hz
0x0D	Vehicle speed	~10 Hz
0x05	Coolant temperature	~1 Hz
0x0F	Intake air temperature	~1 Hz
0x11	Throttle position	~10 Hz
0x2F	Fuel level	~1 Hz
0x46	Ambient temperature	~0.5 Hz

Note what’s missing: oil temperature is not a standard PID on the ND. The Skyactiv-G doesn’t expose it through generic OBD-II, so a third-party dongle can’t read it off the standard PID list. The ECU still measures it — ND2 cars (2019+) display oil temperature digitally in the instrument cluster, fed straight from Mazda’s data. Getting that value into a phone app takes an enhanced Mazda PID and an app that supports custom PID definitions (OBD Fusion or Torque with a community pack). If oil temp is the only thing you’re after, confirm your app supports the enhanced PID before buying.

Why the rate drops when you add gauges

OBD-II is request-response: the adapter asks for a value, the ECU answers, repeat. An ELM327-class adapter manages roughly 8–12 requests per second total; the OBDLink MX+ with its STN chip runs faster. That total is shared across every PID on screen, so if you display five gauges, each one updates around 2 Hz rather than the headline 10 Hz. It’s fine for human-readable gauges and perfectly adequate for spotting a coolant climb. It is not fast enough for serious multi-channel data capture — for that, see data loggers compared, and note that CMU-native logging via the upcoming ScreenTune track edition pulls wheel speed, yaw, and acceleration simultaneously without polling overhead.

Sensible setups

Daily driver. Veepeak BLE+ or OBDLink MX+ with Car Scanner (or OBD Fusion on iOS). Keep coolant temp, intake air temp, and fuel level on screen; read and clear codes when the light comes on.

You also want FORScan. Buy the OBDLink MX+ once. Switch it to MS-CAN for module coding, leave it on standard HS-CAN for monitoring. One adapter, both jobs.

Track days. OBDLink MX+ plus RaceChrono overlays coolant temp and RPM onto your GPS lap trace, which is genuinely useful for catching heat soak over a session. If you’re chasing real lap data, weigh it against dedicated boxes in data loggers compared.