If you own a Yamaha four-stroke from 2002 onwards, from an FX140 to a 2024 GP, you can read its fault memory with a phone. There is no laptop, no cable to a computer and no need to carry a toolbox to the ramp. The method is the same across the FX, VX, GP, EX and FZ series, the SuperJet and the JetBlaster, and below is the sequence that works.
What you need
The M-JET Diagnostic for Yamaha is a small dongle that plugs into the ski's diagnostic connector and talks to an iOS or Android app over Bluetooth. The app is available in six languages (German, English, Spanish, French, Italian and Portuguese). It supports 37 Yamaha four-stroke models, and it identifies the model by itself, so you do not pick one from a list. If you want more detail on how the dongle and phone connect, see diagnostics without a laptop.
The sequence
- Park the ski on the trailer or at the dock, secure, with the lanyard where you can reach it. Do this part standing still. Do not try to read codes while riding.
- Plug the dongle into the diagnostic connector and open the app. Let it find the dongle over Bluetooth, then wait until it has recognised the model. It also reads the engine serial number and control unit data, which you can note for later.
- Open the fault code list. The app shows each code in plain text with a possible cause and a few checks, so you do not need a code table in your pocket.
- Write down every entry exactly as shown. A photo of the screen works just as well.
- Only then look at live values for the circuit the code names. A temperature code, for example, is much easier to interpret next to the actual temperature.
Reading the numbers with care
Fault code numbers are not identical across all Yamahas. The older FX140, FX1000, FX1100 and GP1300R share one set, and the VX1100 of 2005 and all later models use another. Forum posts, manuals and the dash display do not always agree either, which is why the same fault shows up under different numbers online. If a number from a forum differs from what the app says, trust the description in the app.
Safety, and what the scan cannot say
If you work near the fuel system, make sure the area is well ventilated and free of ignition sources. If the engine has to run on land, it needs a water supply and must never run without one. On the water, stop, secure the ski and then look at the phone. Reading a screen at speed is how people hit things.
A fault memory is a list of what the control unit noticed, and it does not know about everything. Cavitation, a worn impeller, a blocked cooling passage, debris in the intake, a worn timing chain on a 2014 or 2015 SVHO, low compression and the amount of fuel the pump actually delivers all produce no code. If you read an empty list and the ski still runs badly, that is a result too. It means the electronics did not catch anything, and you move on to the mechanical side.
Once you have the list, the next question is usually whether to clear it. Reading Yamaha fault codes goes into the details of each step, and the best habit to build is simple: read, write it down, check the live value and decide afterwards.
