Disconnect the vehicle battery (negative terminal).
Relieve fuel system pressure (follow the vehicle service procedure).
Remove the fuel injector rail/injectors (or access them per vehicle design).
Inspect injectors for cracks, leaks, or damaged connectors/O-rings; replace seals as needed.
Use a fuel-injector cleaning kit with the correct adapter for the injector type (port-injection vs. direct-injection).
For bench cleaning:
Mount injectors in the cleaning fixture.
Connect injector electrical leads and fuel lines per kit instructions.
Run the cleaning cycle using injector-safe solvent/cleaner.
Perform spray-pattern verification and flow-rate checks if the kit supports them.
Continue cycles until spray quality and flow targets are met.
For in-tank/in-line chemical cleaning (when supported by the vehicle):
Add the recommended injector-cleaner to the fuel tank per label instructions.
Drive the vehicle to allow the cleaner to circulate through the injectors.
For professional ultrasonic cleaning (if used):
Use an injector-specific ultrasonic cleaner and compatible solution.
Avoid soaking components that are not rated for ultrasonic cleaning (follow shop procedures).
Replace injector O-rings/upper seals (use new parts; lubricate lightly with fuel-safe lubricant if specified).
Reinstall injectors and fuel rail; torque fasteners to factory spec.
Reconnect injector electrical connectors and fuel lines.
Reconnect the battery (negative terminal).
Prime the fuel system and check for leaks at all connections.
Start the engine and verify stable idle and no misfire codes.
Scan for stored/active fuel/ignition/injector-related trouble codes and clear if appropriate after confirming no leaks.
If cleaning does not restore spray/flow or drivability improves briefly then returns, replace the affected injector(s).