What causes the engine malfunction indicator light to come on while the vehicle is still drivable?

[SanCharlie]

Engine malfunction indicator light comes on but the vehicle is still drivable for the following reasons: Emission system malfunction in the engine system: This is mostly caused by fuel quality issues or carbon buildup in the engine, leading to emission system faults. The solution is to first clean the throttle body and intake tract carbon deposits, flush the three-way catalytic converter, then use a diagnostic tool to clear the codes. If the issue disappears, you can continue driving. For fuel quality problems, it's recommended to use higher-octane gasoline or add fuel system cleaner as a mitigation measure. Intermittent faults in engine system sensors: This type of fault is usually caused by occasional improper adjustment of the engine's intake/exhaust camshaft adjustment solenoid valves. The symptoms often include occasional hard starting or slight jerking sensations. When this occurs, you can use specialized diagnostic equipment to read the engine system fault codes - usually historical fault codes can be retrieved.