Hi - looking to replace what appears to be a Diode fitted to a Range Rover Ignition Coil harness. Part number appears to be ERR4019 - this is listed as a diode, presumably a zener type to limit back emf spikes (like the 300V one in the Lucas AB14 amplifiers) from the coil. Can anyone confirm this? Rather an expensive component to replace by the looks of things! Thanks.