Most people are familiar with fuses – they allow your car’s electronics to work while protecting them from over-voltage situations. Relays are similar, but much larger and more powerful. There’s a relay for most of the major components on your car, including the fuel pump, the air conditioner compressor and the starter.

Your starter relay is engaged every time you turn the ignition to run. Voltage is sent through the relay and if it has failed, it stops there. With a dead relay, the starter won’t work and your engine won’t crank. The relay is subjected to very high voltage when you turn the ignition, and this will eventually cause the contact circuit to burn out. It’s also possible for the relay’s energizing circuit to fail.

In terms of lifespan, your starter relay should last a very long time. Many drivers never have to replace theirs, but this isn’t true across the board. Relays can and do fail at any point, including when the car is new. With that being said, starter motor failure is actually more common than a failed relay, and other problems can present similar symptoms, including a dead or dying car battery.

If the starter relay fails, it’s the same as if your starter motor fails in terms of what you can expect – you’ll be stuck where you are until the relay can be replaced. However, there are signs and symptoms that can warn you of an impending failure and knowing these might save you some serious hassle. They include:

  • Starter will not engage at all
  • Starter stays engaged (creating a grinding noise)
  • Starter only works intermittently (usually when the engine is cold)

If you’re experiencing intermittent starts, or the engine won’t crank, there’s a significant possibility that the relay is bad, or that there is something wrong with the starter. Have a mechanic diagnose why your car is not starting, and replace the starter relay or anything else needed to get you back on the road again.

This article originally appeared on YourMechanic.com as How Long Does a Starter Relay Last? and was authored by Valerie Johnston.


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