The 'Check Engine Light,' or MIL (Malfunction Indicator Lamp), illuminates (sometimes flashes with potential fire hazard) on the instrument cluster (IPC) as a very important standard feature for emission control/powertrain performance warning on cars and trucks, since around 1980. However, once the light is triggered it stays ON for a set period of time/ ignition cycles, which effectively 'ties up' its warning usefulness. As a projected improvement, initially disclosed here, a 7-segment display would be next to the MIL. This will indicate an additional fault, by numbered sequence, if unrelated to first fault. This would continue up to 9 (not very likely, but possible). As an example, a MIL illuminates due to an oxygen sensor circuit malfunction.

This is the #1 fault, here. Then, the CCM (Continuous Component Monitor) detects a voltage fault in the fuel level sensor circuit, causing a #2 in the new system to illuminate (while the MIL is still on from before), and so on. Also, during diagnosis, the scantool could indicate the order and mileage of each fault.