Confirmed fixes sourced directly from the manufacturer.
2015 Toyota Auris
The vehicle is suffering from a lack of power and the engine malfunction indicator lamp (MIL) is illuminated. There is a trouble code of P0300 stored in the engine control module (ECM) fault memory
which mentions random/multiple cylinder misfires. After checking the fuel system and replacing the spark plugs, the cause for the lack of power still hasn’t been identified.
This fault has come up before on Auris models with 8NR-FTS engine code and stop-start system up to 24/07/18. The trouble code mentioned is usually accompanied by at least one of these trouble codes: P0301, P0302, P0303, P0304. The fault is due to one or more problematic ignition coils.
To rectify the fault, inspect the production number on each ignition coil. If the production number is before 8208, replace the ignition coil with the latest version. To complete this repair, the engine control module (ECM) will require reprogramming with upgraded software from the manufacturer, and this should rectify the fault.