Signs of Fuel Injector Problems

Updated February 21, 2017

Fuel injectors are the part of a vehicle's fuel system that actually sprays or injects the fuel into the engine's cylinders. Over time, fuel injectors can become either partially or completely clogged. Less expensive fuels may not have as many detergents added to them, which means sediment can more easily build up on the injectors and cause problems. Several signs point toward dirty fuel injectors.

Fuel Economy

It is a good idea to periodically check your vehicle's fuel economy. A decrease in mileage is a sign of problems. If the fuel injectors are becoming clogged and not operating correctly, the engine will not run as efficiently, and your mileage will suffer.

Check Engine

Fuel injector problems can cause the "check engine" light to come on in vehicles that were made from 1996 on. The diminished amount of fuel that is making its way to the vehicle's cylinders can cause "lean misfire," where some of the fuel does not burn completely before exiting the engine via the exhaust system. This condition can trigger a random misfire code, activating the warning light.


The operation of the vehicle can also be affected by fuel injector problems. Rough idle, loss of power, stumbling and stalling are all advanced signs of dirty injectors. In general, dirty fuel injectors will cause the engine to run rough, as it is starved for gas.

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