As above but high engine temperature may be another possibility. That may fit with faulty wiring suggestion. The later model (x244) has a thermostatically controlled high temperature warning. Do not know if your x230? model will have this.
As above but high engine temperature may be another possibility. That may fit with faulty wiring suggestion. The later model (x244) has a thermostatically controlled high temperature warning. Do not know if your x230? model will have this.
To expand on my statment above, my x244 2.8jtd has an engine temperature sensor for the gauge, which also contains a thermostatic switch for the excessive temperature (do not use) warning. If the x230? (model not stated by OP) has a similar feature then an intermittent thermostat or wiring failure is a possibility.