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KOEO Injector Electrical Self Test (Injector Buzz Test)

Key On Engine Off (KOEO) Injector Electrical Self Test is a functional test of the PCM performed on demand with the key on and the engine off. This test determines if the injector circuits and solenoids are electrically operating without fault. All injectors will first buzz (audible feedback of the injector solenoids energizing the injector valves) together for approximately 2 seconds, then each injector will buzz for approximately 1 second in numerical order (1 through 8).

Note: If unable to perform KOEO Injector Electrical Self Test, disconnect IDM connector and check injector high and low side for shorts or opens.

To determine if the injector solenoids and valves are operating, by buzzing all injectors together and then buzzing each injector in numerical sequence (1 through 8).

The IDM stores all historical IDM fault codes; to ensure that the DTC is a hard fault, you must first clear continuous DTCs (be sure to record all IDM fault codes before clearing). After clearing, rerun self test; a fault must be present at the time of testing for the KOEO Injector Electrical Self Test to detect the fault. If a fault is detected, a Diagnostic Trouble Code (DTC) will be the output on the data link at the end of the test when requested by a scan tool. Only a hard fault code (DTC) will be displayed. 

Recommended Procedure:

  • Perform the necessary vehicle preparation and visual inspection
  • Connect the OBDII Scan Tool to the data link connector (DLC) under the dash. Turn off accessories. If vehicle is equipped with an auxiliary powertrain control (rpm control), it must be turned off to perform self tests.
  • Follow operating instructions from the menu.
  • Record DTCs.
  • After test, cycle key to off before running other tests or driving vehicle.

If performing repeated self tests, it may be necessary to unplug glow plug relay to keep battery from going dead. Ignore DTC 0380 while glow plug relay is unplugged.

Possible Causes:

  • Open injector wire.
  • Bad injector connector.
  • Shorted wire or connector.
  • Open solenoid.
  • Defective Injector Drive Module (IDM).

Tools Required:
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent scan tool.

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