DTC Troubleshooting: P0480 (K20C2) - Honda Civic FC/FK 2016-2021

1.

Problem verification:

Problem verification

?1.	Turn the vehicle to the ON mode.

?2.	Clear the DTC with the HDS.

?3.	Select the RADIATOR FAN in the INSPECTION MENU with the HDS.

?4.

Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC
P0480 RFC System Malfunction

Is DTC P0480 indicated?


	YES

The failure is duplicated. Go to step 2.


	NO

Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the RFC unit, the RFC relay, and the PCM. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot.?

2.

Fan shroud assembly visual check:

Fan shroud assembly visual check

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

?2.

Check for these conditions at the radiator fan shroud assembly:

	Interference with fan shroud
	Debris in the fan
	Ice on the fan blades
	Broken or deformed fan
	Broken or deformed fan shroud

Are the conditions OK?


	YES

Go to step 3.


	NO

Repair or replace the damaged parts.?

3.

Fuse check 1:

Fuse check 1

?1.

Check the following fuse.

Fuse	No. A1-2 (30 A)
Location	Under-hood fuse/relay box

Is the fuse OK?


	YES

Go to step 7.


	NO

Go to step 4.

4.

Shorted wire check (+B RFC line):

Shorted wire check (+B RFC line)

?1.	Remove the brown No. A1-2 (30 A) fuse from the under-hood fuse/relay box.

?2.	Remove the RFC relay.

?3.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
Test condition	RFC relay: disconnected
Test point 1	RFC relay 4P socket No. 1
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the +B RFC wire between the No. A1-2 (30 A) fuse in the under-hood fuse/relay box and the RFC relay. If the wire is OK, replace the under-hood fuse/relay box. Also replace the No. A1-2 (30 A) fuse.?


	NO

The +B RFC wire is OK. Go to step 5.

5.

Shorted wire check (RFC DRIVER RLY OUT line):

Shorted wire check (RFC DRIVER RLY OUT line)

?1.

Disconnect the following connector.

RFC unit connector A (2P)

?2.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	RFC relay: disconnected
	RFC unit connector A (2P): disconnected
Test point 1	RFC relay 4P socket No. 2
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the RFC DRIVER RLY OUT wire between the RFC relay and the RFC unit. Also replace the No. A1-2 (30 A) fuse in the under-hood fuse/relay box.?


	NO

The RFC DRIVER RLY OUT wire is OK. Go to step 6.

6.

Relay check:

Relay check

?1.	Test the RFC relay.

Is the relay OK?


	YES

Replace the No. A1-2 (30 A) fuse in the under-hood fuse/relay box, then recheck. If the fuse is brown again, replace the RFC unit.?


	NO

Replace the RFC relay.?

7.

Determine possible failure area (RFC relay control circuit, others):

Determine possible failure area (RFC relay control circuit, others)

?1.	Jump the SCS line with the HDS, and wait more than 1 minute.

?2.

Disconnect the following connector.

PCM connector A (50P)

?3.

Measure the voltage between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (50P): disconnected
Test point 1	PCM connector A (50P) No. 30
Test point 2	Body ground

Is there battery voltage?


	YES

Go to step 11.


	NO

Go to step 8.

8.

Open wire check (RFC RLY CL- line):

Open wire check (RFC RLY CL- line)

?1.	Remove the RFC relay.

?2.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (50P): disconnected
	RFC relay: disconnected
Test point 1	RFC relay 4P socket No. 3
Test point 2	PCM connector A (50P) No. 30

Is there continuity?


	YES

The RFC RLY CL- wire is OK. Go to step 9.


	NO

Repair an open in the RFC RLY CL- wire between the PCM (A30) and the RFC relay.?

9.

Relay check:

Relay check

?1.	Test the RFC relay.

Is the relay OK?


	YES

Go to step 10.


	NO

Replace the RFC relay.?

10.

Fuse check 2:

Fuse check 2

?1.

Check the following fuse.

Fuse	No. A5 (5 A)
Location	Under-hood fuse/relay box

Is the fuse OK?


	YES

Repair an open in the RFC RLY CL+ wire between the No. A5 (5 A) fuse and the RFC relay.?


	NO

Repair a short in the RFC RLY CL+ wire between the No. A5 (5 A) fuse and the RFC relay. Also replace the No. A5 (5 A) fuse.?

11.

Shorted wire check (FAN CONTROL line):

Shorted wire check (FAN CONTROL line)

?1.

Disconnect the following connector.

RFC unit connector B (3P)

?2.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
Test condition	PCM connector A (50P): disconnected
	RFC unit connector B (3P): disconnected
Test point 1	PCM connector A (50P) No. 17
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the FAN CONTROL wire between the PCM (A17) and the RFC unit.?


	NO

The FAN CONTROL wire is not shorted. Go to step 12.

12.

Open wire check (FAN CONTROL line):

Open wire check (FAN CONTROL line)

?1.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (50P): disconnected
	RFC unit connector B (3P): disconnected
Test point 1	RFC unit connector B (3P) No. 1
Test point 2	PCM connector A (50P) No. 17

Is there continuity?


	YES

The FAN CONTROL wire is OK. Go to step 13.


	NO

Repair an open in the FAN CONTROL wire between the PCM (A17) and the RFC unit.?

13.

Open wire check (+B RFC line):

Open wire check (+B RFC line)

?1.	Remove the RFC relay.

?2.

Measure the voltage between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
Test condition	PCM connector A (50P): disconnected
	RFC unit connector B (3P): disconnected
	RFC relay: disconnected
Test point 1	RFC relay 4P socket No. 1
Test point 2	Body ground

Is there battery voltage?


	YES

The +B RFC wire is OK. Go to step 14.


	NO

Repair an open in the +B RFC wire between the No. A1-2 (30 A) fuse in the under-hood fuse/relay box and the RFC relay.?

14.

Relay check:

Relay check

?1.	Test the RFC relay.

Is the relay OK?


	YES

Go to step 15.


	NO

Replace the RFC relay.?

15.

Open wire check (RFC DRIVER RLY OUT line):

Open wire check (RFC DRIVER RLY OUT line)

?1.	Reinstall the RFC relay.

?2.	Reconnect PCM connector A (50P).

?3.	Exit the SCS mode with the HDS.

?4.

Disconnect the following connector.

RFC unit connector A (2P)

?5.	Turn the vehicle to the ON mode.

?6.

Measure the voltage between test points 1 and 2.

Test condition	Vehicle ON mode
	RFC unit connector B (3P): disconnected
	RFC unit connector A (2P): disconnected
Test point 1	RFC unit connector A (2P) No. 1
Test point 2	Body ground

Is there battery voltage?


	YES

The RFC DRIVER RLY OUT wire is OK. Go to step 16.


	NO

Repair an open in the RFC DRIVER RLY OUT wire between the RFC relay and the RFC unit.?

16.

Open wire check (GND line):

Open wire check (GND line)

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

?2.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	RFC unit connector B (3P): disconnected
	RFC unit connector A (2P): disconnected
Test point 1	RFC unit connector A (2P) No. 2
Test point 2	Body ground

Is there continuity?


	YES

The GND wire is OK. Go to step 17.


	NO

Repair an open in the GND wire between the RFC unit and G401 (type A), G402 (type B).?

17.

RFC unit check (substitution):

RFC unit check (substitution)

?1.	Substitute a known-good RFC unit.

?2.	Reconnect all connectors.

?3.	Turn the vehicle to the ON mode.

?4.	Clear the DTC with the HDS.

?5.	Select the RADIATOR FAN in the INSPECTION MENU with the HDS.

?6.

Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC
P0480 RFC System Malfunction

Is DTC P0480 indicated?


	YES

Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM, then recheck. If DTC P0480 goes away and the PCM was substituted, replace the original PCM.?


	NO

Replace the original RFC unit.?