DTC Troubleshooting: P0131
DTC P0131: A/F Sensor (Sensor 1) Circuit Low Voltage
NOTE: Before you troubleshoot, review the general troubleshooting information.

DTC Description
Confirmed DTC
Pending DTC
P0131 A/F Sensor (Sensor 1) Circuit Low Voltage
    

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.
Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.

?5.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
P0131 A/F Sensor (Sensor 1) Circuit Low Voltage
    

Is DTC P0131 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) 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.
A/F sensor (Sensor 1) internal circuit check:

A/F sensor (Sensor 1) internal circuit check
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connector.
A/F sensor (Sensor 1) 6P connector

?3.
At the A/F sensor (Sensor 1) side, check for continuity between the following test points and body ground individually.
Test condition
Vehicle OFF (LOCK) mode
 
A/F sensor (Sensor 1) 6P connector: disconnected

Connector
Terminal
A/F sensor (Sensor 1) 6P connector (male terminals) (sensor side):
No. 1
No. 3
No. 4
No. 6


Is there continuity at any terminal?

     
YES
     
     
     
     
NO
     
     
     
Go to step 3.
3.
Shorted wire check (LAF lines):

Shorted wire check (LAF lines)
?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 the following test points and body ground individually.
Test condition
Vehicle OFF (LOCK) mode
 
A/F sensor (Sensor 1) 6P connector: disconnected
 
PCM connector No. 1 (96P): disconnected

Connector
Terminal
A/F sensor (Sensor 1) 6P connector (female terminals):
No. 1
No. 3
No. 4
No. 6


Is there continuity at any terminal?

     
YES
     
     
     
Repair a short in the wire(s) between PCM connector No. 1 terminals No. 54 (LAF VN wire), No. 36 (LAF VG wire), No. 55 (LAF CA wire), and/or No. 37 (LAF CP wire) and the A/F sensor (Sensor 1).?
     
NO
     
     
     
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 P0131 goes away and the PCM was substituted, replace the original PCM.?