Would a bad alternator cause the check engine light come on?

Tiny
DANE1962
  • MEMBER
  • 2004 CADILLAC SEVILLE
  • 131,411 MILES
We have been trying to figure out why the check engine light is on. And we just found out that the alternator is not working. Was wondering if that could be the reason the check engine light is on.
Thursday, December 1st, 2011 AT 3:51 PM

1 Reply

Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I'm Danny.

Yes, a failing or defective alternator can cause a check engine light. Most auto parts stores will test your alternator for free. Here are two tutorials showing how to test and replace an alternator:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

https://www.2carpros.com/articles/how-to-replace-an-alternator

I would also suggest checking the codes that might be stored in your cars computer from the check engine light being on. If you don't have access to a scanner or code reader most auto parts stores have a tool loaner program and can rent you one. Here is a tutorial showing how to check for codes:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

After you perform these tests get back to us with the information and we can then properly diagnose these issues. Hope this helps and thanks for using 2CarPros.
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Monday, December 7th, 2020 AT 8:01 PM

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