DTC Troubleshooting: P0685
DTC P0685: A/F Sensor (Sensor 1) Heater Power Source Circuit Open
NOTE: Before you troubleshoot, review the general troubleshooting information.

DTC Description
Confirmed DTC
Pending DTC
P0685 A/F Sensor (Sensor 1) Heater Power Source Circuit Open
    

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
P0685 A/F Sensor (Sensor 1) Heater Power Source Circuit Open
    

Is DTC P0685 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.
Open wire check (+B DBW line):

Open wire check (+B DBW line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Relay circuit board: removed
Test point 1
Relay circuit board connector C (18P) (female terminals) No. 14:
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The +B DBW wire is OK. Go to step 5.
     
NO
     
     
     
Repair an open in the +B DBW wire between the relay circuit board and the No. A9 (15 A) fuse in the under-hood fuse/relay box.?
5.
Open wire check (FI SUB RLY OUT/IGPS(LAF) line):

Open 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
A/F sensor (Sensor 1) 6P connector (female terminals) No. 2:



Is there continuity?

     
YES
     
     
     
The FI SUB RLY OUT/IGPS(LAF) wire is OK. Go to step 6.
     
NO
     
     
     
Repair an open in the FI SUB RLY OUT/IGPS(LAF) wire between the relay circuit board and the A/F sensor (Sensor 1).?
6.
Open wire check (AFHT line):

Open 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
A/F sensor (Sensor 1) 6P connector (female terminals) No. 5:
Test point 2
PCM connector No. 1 (96P) No. 16


Is there continuity?

     
YES
     
     
     
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 P0685 goes away and the PCM was substituted, replace the original PCM.?
     
NO
     
     
     
Repair an open in the AFHT wire between PCM connector No. 1 terminal No. 16 and the A/F sensor (Sensor 1).?