How does the Prius (2011 model if it matters) re-ignite the gas motor when it needs to be used without wearing down the ignition system too much?

Since the Prius is a Hybrid the gas engine is not always in use thus it needs to be re-ignited from time to time but how does it do this without killing the ignition system since it happens so often?

  • The ignition system is used during the entire time the engine is running, not just during startup. It's not like starting a fire. Do you have a maintenance or repair question?
    – cory
    Commented Jan 17, 2017 at 14:02
  • 1
    I'd say the question is related to keeping the vehicle in good shape. I'm asking how does the engine get re-ignited so often without burning out the igniter? Traditional cars just ignite once but does the engine have to be re-ignited since it turns itself off?
    – Sie
    Commented Jan 17, 2017 at 14:14
  • It's not a fire, that you light once and add fuel once in a while. It's igniting the spark plugs the entire time the engine is running. Please look up how an internal combustion engine works. There are plenty of resources available for this already, it doesn't need to be repeated here.
    – cory
    Commented Jan 17, 2017 at 14:23
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    might be a language mistake? Could the question be about the starter motor instead of the ignition?
    – Hobbes
    Commented Jan 17, 2017 at 14:34
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    @cory Lets also be clear, general questions about automotive and engine technology are within the scope of this SE. It is not just a repair and maintenance SE.
    – cdunn
    Commented Jan 18, 2017 at 17:02

1 Answer 1


The Prius doesn't start traditionally. It actually has two motors, MG1 and MG2 (MG = Motor Generator.) MG1 replaces a traditional starter motor in the sense that it is responsible for spinning up the engine. If you've ever started a Prius while stopped, you might notice that it sounds different. That's because the computer first adjusts timing to reduce compression, then spins the crankshaft using MG1. Once RPMs are high enough (and oil pressure is up) the computer introduces fuel and spark and readjusts timing to provide normal compression. This is why you never hear a traditional cranking sound when the engine is started.

  • 1
    It also helps that MG1 is much more powerful than a starter motor, so it can spin up the engine to idling speed.
    – Hobbes
    Commented Jan 18, 2017 at 10:49

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