Will a bad starter cause check engine light to come on?

While a failing starter can potentially prevent your vehicle from starting, it typically does not directly cause the check engine light (CEL) to illuminate. The CEL is usually triggered by issues related to the engine's performance, emissions control systems, or other electronic components.

Here are a few reasons why the check engine light might come on, but they are not directly related to a bad starter:

Loose Gas Cap: A loose or missing gas cap can cause a vacuum leak in the fuel system, which can trigger the check engine light.

Oxygen Sensor Issues: A faulty oxygen sensor can affect the vehicle's air-fuel mixture and lead to the illumination of the CEL.

Catalytic Converter Problems: Issues with the catalytic converter, which helps reduce emissions, can cause the check engine light to turn on.

Engine Misfire: A misfire, where the engine fails to burn fuel properly in one or more cylinders, can cause the CEL to come on.

Faulty Spark Plugs or Ignition Coils: Problems with spark plugs or ignition coils can disrupt the ignition process and trigger the check engine light.

Evaporative Emissions System Issues: Faults in the evaporative emissions system, which prevents fuel vapors from escaping into the atmosphere, can cause the check engine light to turn on.

If the check engine light is illuminated, it is advisable to have your vehicle diagnosed by a qualified mechanic or automotive technician. They can use specialized diagnostic tools to read and interpret trouble codes stored by the vehicle's onboard computer, helping to determine the root cause of the issue and recommend the appropriate repairs.