QPKING M4 Motorcycle Diagnostic Tool for Harley-Davidson — 2.8" Screen, 4P/6P & OBD2 Cables, 17 Languages

The QPKING M4 is a dedicated diagnostic scanner built to read and clear fault codes, display live data and run supported service routines on Harley-Davidson motorcycles with 4-pin or 6-pin ports.

Designed specifically for compatible Harley-Davidson models, the M4 gives riders and independent technicians a compact way to inspect ECU information, monitor sensors in real time and perform manufacturer-style resets and active tests where supported. It pairs a clear 2.8-inch screen with two cables to handle Harley round-port communication and basic OBD2 engine checks for cars. The unit runs from the motorcycle's 12 V supply, supports 17 languages on-device, and accepts updates via SD card.

Which Harley functions can the M4 perform?

The M4 supports a range of Harley-specific operations depending on the bike’s year, model and ECU. Typical capabilities include reading and erasing diagnostic trouble codes, viewing live sensor data streams and accessing available system modules. Some service procedures and advanced functions may be limited by the motorcycle’s software or model year.

• Read and clear supported fault codes from available ECUs.
• View live data—RPM, temperatures, sensor voltages and more—when available.
• Access system and ECU information for supported models.
• Perform supported service resets and active tests as allowed by the motorcycle.

How do the two included cables differ and when should I use each?

The kit ships with a Harley 4P/6P cable and a standard OBD2 16P cable so you can connect to round Harley diagnostic ports or a car OBD2 port. Use the Harley cable to access model-specific functions, resets and active tests; the OBD2 lead provides basic engine code reading and live data on compatible cars.

• Harley 4P/6P cable: primary tool for Harley diagnostics and supported service procedures.
• OBD2 16P cable: basic engine fault reading, clearing and live data for cars.
• Choose cable based on vehicle connector type and desired diagnostic depth.

What are the practical limits and update process for this scanner?

The M4 is a no-battery, powered tool that relies on the vehicle’s 12 V supply, so it must remain connected while in use. Coverage of functions like ABS bleeding or advanced adjustments varies by year and ECU; for example, ABS bleeding is available on some models through 2023 but not on 2024+ units. Firmware and function updates are applied with the official update package and a FAT32-formatted SD card without removing power.

• Tool requires 12 V bike power—no internal battery.
• ABS bleeding limited to supported years and ECUs (check compatibility).
• Update firmware via provided package and FAT32 SD card while powered.

Who this tool is for: The QPKING M4 is aimed at Harley-Davidson owners, DIY mechanics and small motorcycle shops that need an affordable, portable scanner for troubleshooting, live-data checks and routine service operations on compatible Harley models. It is best suited for those who verify their bike’s connector type and model-year compatibility in advance and who want a multilingual device for straightforward diagnostics without dealer-only software.