DTC Troubleshooting: P0686
DTC P0686: A/F Sensor (Sensor 1) Heater Power Source Circuit Short to Ground
NOTE: Before you troubleshoot, review the general troubleshooting information.

DTC Description
Confirmed DTC
Pending DTC
P0686 A/F Sensor (Sensor 1) Heater Power Source Circuit Short to Ground
    

1.
Problem verification:

Problem verification
?1.
Turn the vehicle to the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Start the engine.

?4.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
P0686 A/F Sensor (Sensor 1) Heater Power Source Circuit Short to Ground
    

Is DTC P0686 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 relay circuit board (PGM-FI subrelay circuit), the A/F sensor (Sensor 1), 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.
Fuse check:

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

?2.
Check the following fuse.
Fuse
No. A9 (15 A)
Location
Under-hood fuse/relay box

Is the fuse OK?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Repair a short in the No. A9 (15 A) fuse circuit. Also replace the No. A9 (15 A) fuse.?
3.
Relay circuit board check:

Relay circuit board check
?1.
Remove and test the relay circuit board.

Is the relay circuit board OK?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
4.
Shorted wire check (FI SUB RLY OUT/IGPS(LAF) line):

Shorted wire check (FI SUB RLY OUT/IGPS(LAF) line)
?1.
Disconnect the following connector.
A/F sensor (Sensor 1) 6P connector

?2.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
 
A/F sensor (Sensor 1) 6P connector: disconnected
Test point 1
Relay circuit board connector C (18P) (female terminals) No. 1:
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short in the FI SUB RLY OUT/IGPS(LAF) wire between the relay circuit board and the A/F sensor (Sensor 1).?
     
NO
     
     
     
The FI SUB RLY OUT/IGPS(LAF) wire is OK. Go to step 5.
5.
Shorted wire check (AFHT line):

Shorted wire check (AFHT line)
?1.
Jump the SCS line with the HDS, and wait more than 1 minute.


?2.
Disconnect the following connector.
PCM connector No. 1 (96P)

?3.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
 
A/F sensor (Sensor 1) 6P connector: disconnected
 
PCM connector No. 1 (96P): disconnected
Test point 1
PCM connector No. 1 (96P) No. 16
Test point 2
Body ground

Is there continuity?

     
YES
     
     
     
Repair a short in the AFHT wire between PCM connector No. 1 terminal No. 16 and the A/F sensor (Sensor 1).?
     
NO
     
     
     
The AFHT wire is OK. 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 P0686 goes away and the PCM was substituted, replace the original PCM.?