Can worn-out spark plugs reduce fuel efficiency in a Toyota Prius?

Home > Gari Forums > Toyota Forums > Toyota Prius Forums > Toyota Prius Spark Plug Problems Forums

Can worn-out spark plugs reduce fuel efficiency in a Toyota Prius?

A weak o r misfiring spark can cause incomplete combustion, leading to increased fuel consumption. How much does spark plug wear impact fuel economy, and how can Prius owners check for this issue?

Zarnish asked on 14 Feb 2025 16:33:14 pm

1 Answer

21 views |

Car Mechanic Expert - on 14 Feb 2025 16:44:09 pm

Yes, worn-out spark plugs can significantly reduce fuel efficiency:

A weak o r misfiring spark means the air-fuel mixture is not burned properly, leading to incomplete combustion.
This inefficiency can cause the engine to consume more fuel to produce the same power output.

Impact on fuel economy: Depending on the extent of the wear, you could experience a 5-10% in fuel efficiency. If your fuel economy has suddenly ped without any apparent cause, worn spark plugs might be the issue.

Checking for fuel efficiency loss: You can monitor the fuel consumption using your trip meter and fuelly app o r a similar tool to track average consumption.