DTC Troubleshooting: P1157
DTC P1157: A/F Sensor (Sensor 1) AFS Circuit High Voltage
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P1157 A/F Sensor (Sensor 1) AFS Circuit High Voltage
      

1.
Problem verification:

Problem verification
?1.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Start the engine, and wait for 1 minute.

?4.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P1157 A/F Sensor (Sensor 1) AFS Circuit High Voltage
     

Is DTC P1157 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 A/F sensor (Sensor 1), the PGM-FI subrelay, and the PCM.?
2.
Open wire check (AFS+ line):

Open wire check (AFS+ line)
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Jump the SCS line with the HDS.


?3.
Disconnect the following connectors.

?4.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0) or OFF mode
 
A/F sensor (Sensor 1) 4P connector: disconnected
 
PCM connector C (51P): disconnected
Test circuit
AFS+
Test point 1
A/F sensor (Sensor 1) 4P connector No. 2 (RED)
Test point 2
PCM connector C (51P) No. 48 (RED)


Is there continuity?

     
YES
     
     
     
The AFS+ wire is OK. Go to step 3.
     
NO
     
     
     
Repair an open in the AFS+ wire between the PCM (C48) and the A/F sensor (Sensor 1), then do the repair verification.
3.
Open wire check (AFS- line):

Open wire check (AFS- line)
?1.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0) or OFF mode
 
A/F sensor (Sensor 1) 4P connector: disconnected
 
PCM connector C (51P): disconnected
Test circuit
AFS-
Test point 1
A/F sensor (Sensor 1) 4P connector No. 1 (RED/YEL)
Test point 2
PCM connector C (51P) No. 47 (RED/YEL)


Is there continuity?

     
YES
     
     
     
The AFS- wire is OK. Go to step 4.
     
NO
     
     
     
Repair an open in the AFS- wire between the PCM (C47) and the A/F sensor (Sensor 1), then do the repair verification.
4.
A/F sensor (Sensor 1) check (substitution):

A/F sensor (Sensor 1) check (substitution)
?1.
Substitute a known-good A/F sensor (Sensor 1).

?2.
Reconnect all connectors.

?3.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

?4.
Reset the PCM with the HDS.


?5.
Do the PCM idle learn procedure.

?6.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P1157 A/F Sensor (Sensor 1) AFS Circuit High Voltage
     

Is DTC P1157 indicated?

     
YES
     
     
     
The failure is duplicated. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then do the repair verification.
     
NO
     
     
     
Replace the original A/F sensor (Sensor 1), then do the repair verification.
Repair verification:

?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Reconnect all connectors.

?3.
Exit the SCS mode with the HDS.


?4.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

?5.
Reset the PCM with the HDS.


?6.
Do the PCM idle learn procedure.

?7.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P1157 A/F Sensor (Sensor 1) AFS Circuit High Voltage
     


Is DTC P1157 indicated?

     
YES
     
     
     
Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the PCM. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1.
     
NO
     
     
     
Troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.?