P0151-O2 SENSOR 2/1 CIRCUIT LOW





For a complete wiring diagram Refer to Section 8W.


  • When Monitored:

    Engine running for less than 30 seconds and the O2 Sensor Heater Temperature is less than 251°C (484°F) with battery voltage greater 10.99 volts.

  • Set Condition:

    The oxygen sensor signal voltage is below 2.5196 volts for 6 seconds after starting engine. Two Trip Fault. Three good trips to turn off the MIL.


Possible Causes
 
(K902) O2 UPSTREAM RETURN CIRCUIT SHORTED TO GROUND
 
(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO GROUND
 
(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO THE (K902) O2 UPSTREAM RETURN CIRCUIT
 
(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO THE (Z42) HEATER GROUND CIRCUIT
 
O2 SENSOR
 
PCM
 


Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).



Diagnostic Test

1.O2 SENSOR BELOW 2.52 VOLTS





Is the voltage below 2.52 volts?

Yes
  • Go To 2


No

2.(K43) O2 2/1 SIGNAL CIRCUIT






Is the O2 Sensor voltage above 4.8 volts?

Yes
  • Go To 3


No
  • Go To 5

3.O2 SENSOR





Is the voltage at 2.5 volts?

Yes


No
  • Go To 4

4.(K902) O2 UPSTREAM RETURN CIRCUIT SHORTED TO GROUND







Is the resistance below 100 ohms?

Yes


No
  • Go To 8

5.(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO GROUND







Is the resistance below 100 ohms?

Yes


No
  • Go To 6

6.(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO THE (K902) O2 UPSTREAM RETURN CIRCUIT





Is the resistance below 100 ohms?

Yes


No
  • Go To 7

7.(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO THE (Z42) HEATER GROUND CIRCUIT





Is the resistance below 100 ohms?

Yes


No
  • Go To 8

8.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.




Were there any problems found?

Yes


No