The company booked a £3.1bn reduction in the value of its plants and other investments leading to a £3.4bn quarterly loss, its biggest to date.
Carmakers are being hit by stronger regulations and demand for cleaner models.
Sales for the quarter were £6.2bn, down from £6.3bn a year earlier. It sold 144,602 vehicles, down from 154,447.
Jaguar chief executive Ralf Speth said: “Jaguar Land Rover reported strong third-quarter sales in the UK and North America, but our overall performance continued to be impacted by challenging market conditions in China.”
Excluding the write-down, which affects its balance sheet but has no effect on cash, the company posted a loss of £273m.
Much of the firm’s model range is currently diesel-powered, while diesel sales in Europe have been falling.
Jaguar Land Rover, which is owned by India’s Tata Motors, has embarked on a major restructuring programme to prepare for the future and boost profitability.
It has already announced plans to cut thousands of jobs.
It has now accepted that the value of its existing investments – such as factories, equipment and model designs – is substantially lower than previously thought, said BBC business correspondent Theo Leggett.