The fault light of the Range Rover is on when the engine is under heavy load

Q: A Range Rover has a fault light on when the engine is under heavy load. I went to the 4S shop for inspection and replaced the water temperature sensor and thermostat, but the problem was not solved. Now I suspect that the engine computer is faulty. The technician of the 4S shop said that the engine computer needs to be replaced. Is this a problem with the computer itself?

A: The cause of the failure of the Range Rover described in the question is not the water temperature sensor and the engine computer, but is generally caused by the failure of the front oxygen sensor. Usually, replacing the front oxygen sensor can restore the vehicle to normal. Perhaps the failure of the oxygen sensor causes the mixture ratio to be imbalanced, resulting in abnormal water temperature, and the computer mistakenly judges it as a water temperature sensor failure. The fault worsens over time, and sometimes it is necessary to replace the front and rear oxygen sensors and the three-way catalytic converter to restore the vehicle to normal. Therefore, repairing as soon as possible can reduce losses.