Hi Sarah.....welcome to the Forum
See Also
How Long Will Check Engine Light Stay On After Repair - NOLA Automotive Repairs IncHow to Reset a Reduced Engine Power Light: A Quick Fix & MoreSteam Support :: Update & Installation IssuesVauxhall error code 82 - change oil, clear and carry on? Or top up and wait for next service?Its an odd one!
Generally code 84 means reduced power delivery (going into limp home mode) but can be caused by many different things.
If it is happening when indicating right, I would firstly check all the lighting and ensure that the correct bulbs are fitted.
It has happened on cars I have previously encountered with defective brake light bulbs and the engine went into limp home mode.
If nothing is wrong with the lighting circuit then I would strip off the plastics surrounding the indicator switch and check that no wiring has chaffed through and is affecting the ignition switch, etc
Please do let us know what you find
