Is it necessary to replace all 4 fuel injectors if one is bad?

[McGiselle]

It is not necessary; you only need to replace the damaged fuel injector. Below is some related information about fuel injectors: 1. Fuel injector cleaning cycle: Generally, it is recommended to clean them every 20,000-30,000 kilometers. If the vehicle condition is good and the fuel quality is high, this interval can be extended to 40,000-60,000 kilometers. 2. Hazards of long-term neglect of fuel injector cleaning: If fuel injectors are not cleaned for a long time, clogging will become more severe, leading to poor fuel injection, improper spray angle and atomization, which can cause the engine to idle roughly, accelerate poorly, or perform inadequately under full load. This results in reduced engine power and increased fuel consumption.