* Matching Characteristics: Fuel injectors wear at different rates, but they're designed to work together as a set. Replacing just one with a new injector introduces a mismatch in spray pattern, flow rate, and impedance. This can lead to rough running, poor fuel economy, and even damage to the catalytic converter.
* Potential for Further Problems: If one injector failed, there's a chance others are nearing the end of their lifespan. Replacing only one might just delay the inevitable need to replace the rest soon after.
* Diagnosis: It's crucial to determine *why* the injector failed. A single bad injector might be a symptom of a larger problem (e.g., low fuel pressure, faulty fuel pump, dirty fuel). Addressing the root cause is more important than just replacing the injector.
In short, while possible, it's usually more cost-effective and beneficial in the long run to replace all the fuel injectors simultaneously. This ensures consistent fuel delivery and prevents potential future problems. The cost difference between replacing one and replacing all might be surprisingly small, given the labor involved.
