How does the dealer know if fuel injectors need cleaned?

The dealer usually performs a fuel injector service based on mileage or if the vehicle is experiencing certain symptoms, such as: idling, reduced fuel efficiency, misfires or stalls, and a lack of power. However, they don't typically know unless diagnostics are run.

Here are some common ways a technician can inspect fuel injectors:

- Visual inspection: The technician will look for any obvious signs of damage or wear on the fuel injectors, such as leaks, cracks, or corrosion.

- Fuel pressure test: The technician will check the fuel pressure in the system to make sure it is within specifications. If the fuel pressure is too low, it can cause the fuel injectors to not get enough fuel to properly operate.

- Fuel injector flow test: The technician will test the flow rate of each fuel injector to make sure it is within specifications. If a fuel injector is not flowing enough fuel, it can cause the engine to run lean and misfire.

- Computer scan: The technician may also use a computer scan tool to check for any codes that may be related to the fuel injectors. Some fuel injector problems can be detected by the computer's self-diagnostic system.

If the technician determines that the fuel injectors need to be cleaned, they will typically use a chemical cleaner to remove any deposits that may be blocking the fuel flow. In some cases, the fuel injectors may need to be replaced if they are damaged or worn out.