Yamaha FX140: Overheat Indicator On and Engine in Limp Mode

On an FX140 the overheat indicator lights up and the engine only runs in a restricted way. In forums you often hear this after several sensors were replaced on a hunch. With M-JET DIAGNOSTIC you see whether the control unit really detects overtemperature.

What you check in the app

• Engine temperature live: does it rise plausibly with load or does it jump?
• Fault memory: on this control unit code 21 stands for the engine temperature sensor
• Battery voltage: too low a voltage produces false messages
• Does the message return immediately after cooling down?

Sensor or cooling water path?

If the app shows a plausibly rising temperature, the engine really is hot. Then intake grate, pump and water path are the next step. If it shows an impossible value straight away or jumps, the sensor or wiring is suspect. That way you do not replace sensors on a hunch. Never run the engine on land without a water supply.

Related topics

• Yamaha FX140 Fault Codes: List and Meaning
• Yamaha FX140 No Longer Reaches Top Speed
• Yamaha WaveRunner Overheating and Temperature Sensor
• Diagnostics and fault codes for your Yamaha model
• All Yamaha WaveRunner diagnostics topics

Everything runs via app over Bluetooth, for Yamaha WaveRunners from model year 2002 to today. Learn more about the M-JET DIAGNOSTIC for Yamaha WaveRunner.