Yamaha 1.9 Litre: Overheat Alarm, Sensor or Water Path?

A temperature warning on the 1.9-litre generation means stop and clarify. M-JET DIAGNOSTIC shows you three measuring points side by side and helps you decide whether the sensor or the water path is the problem.

What you compare

• Code 15: engine temperature sensor
• Code 65: exhaust manifold water temperature
• Code 41: thermo sensor
• Curve at idle, planing and full load

Flow first

The rule of thumb from forums for Yamaha overheat messages: in most cases a flow problem is behind it, such as a clogged exhaust water hole, a blocked inlet, cavitation or a chipped impeller. If the values in the app rise plausibly with load, that is the way. If all sensors show normal values and the alarm sounds anyway, the thermo switch belongs on the list. Never run the engine on land without a water supply, and do not ride on with real overheating.

Related topics

• Yamaha 1.9-Litre FX, GP and VX (from 2024) Fault Codes: List
• Yamaha 1.9 Litre: Classify the Thermo Sensor Message (Code 41)
• 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.