The ignition HT leads connects the distributor to the spark plugs in a vehicles’ ignition. There is one ignition HT lead for each spark plug. Power is sent from the 12volt battery to the coil. This coil converts the power of the battery in to a much higher current, and the current is then sent to the distributor. The distributor has a rotor inside which when hitting a set point tells the coil to transmit the electrical pulse. This pulse is transferred through the ignition HT leads to the spark plugs and is used to ignite the fuel and air combination.

If a ignition HT lead is damaged, the circuit will not be completed to the spark plug and could result in engine misfire or the vehicle, stuttering or cause it to not start. These leads are also prone to shifting and coming loose of the start plug. With any engine problems you are likely to get an error message on your dashboard suggesting an engine check. If this occurs, be sure to check the ignition HT leads and buy immediate replacements if any of these appear worn or damaged.