DTC Troubleshooting: P0506 (K20C1) - Honda Civic FC/FK 2016-2021

DTC Troubleshooting: P0506

DTC P0506: Idle Control System RPM Lower Than Expected

NOTE: Before you troubleshoot, review the general troubleshooting information.

DTC Description	Confirmed DTC	Pending DTC
P0506 Idle Control System RPM Lower Than Expected

Problem verification:

Problem verification

?1.	Turn the vehicle to the ON mode.

?2.	Clear the DTC with the HDS.

?3.	Start the engine and let it idle for 10 seconds or more.

?4.

Check for these conditions in the DATA LIST with the HDS.

	VEHICLE SPEED is 0 mph (0 km/h)
	AF FB (ST FUEL TRIM) between 0.75 and 1.25
	FSS is CLOSED

Signal	Current conditions
Signal	Values	Unit
VEHICLE SPEED
AF FB (ST FUEL TRIM)
FSS

?5.

Monitor the OBD STATUS for DTC P0506 in the DTCs MENU with the HDS.

DTC Description	OBD STATUS
P0506 Idle Control System RPM Lower Than Expected

Does the HDS indicate FAILED?


	YES

The failure is duplicated. Go to step 2.


	NO

If the HDS indicates PASSED, go to step 3. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 1-4 and recheck.

Throttle body visual check:

Throttle body visual check

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.	Disconnect the throttle body inlet pipe and the throttle body connector tube from the throttle body.

?3.	Check for dirt, carbon, or damage in the throttle bore.

Is there dirt, carbon, or damage in the throttle bore?


	YES

If there is dirt or carbon, clean the throttle body. Also check for damage to the air cleaner element. If there is damage in the throttle bore, replace the throttle body.?


	NO

The throttle body is OK. Check the A/C system, then go to step 4.

Throttle body visual check:

Throttle body visual check

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.	Disconnect the throttle body inlet pipe and the throttle body connector tube from the throttle body.

?3.	Check for dirt, carbon, or damage in the throttle bore.

Is there dirt, carbon, or damage in the throttle bore?


	YES

If there is dirt or carbon, clean the throttle body. Also check for damage to the air cleaner element. If there is damage in the throttle bore, replace the throttle body.?


	NO

The throttle body is OK. Go to step 4.

Idle control system check:

Idle control system check

?1.	Reconnect the throttle body inlet pipe and the throttle body connector tube.

?2.	Turn the vehicle to the ON mode.

?3.	Clear the DTC with the HDS.

?4.	Start the engine and let it idle for 10 seconds or more.

?5.

Check for these conditions in the DATA LIST with the HDS.

	VEHICLE SPEED is 0 mph (0 km/h)
	AF FB (ST FUEL TRIM) between 0.75 and 1.25
	FSS is CLOSED

Signal	Current conditions
Signal	Values	Unit
VEHICLE SPEED
AF FB (ST FUEL TRIM)
FSS

?6.

Monitor the OBD STATUS for DTC P0506 in the DTCs MENU with the HDS.

DTC Description	OBD STATUS
P0506 Idle Control System RPM Lower Than Expected

Does the HDS indicate PASSED?


	YES

Intermittent failure, the system is OK at this time. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot.?


	NO

If the HDS indicates FAILED, check the A/C system, then recheck. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 4-5 and recheck.?