i had a 0138 code, reconnected a loose connector at the sensor and it worked , i could watch the 0-1 v change on both o2 sensors. all was well for 2 days. now the same, #2 is bad again??
i use an actron reader, seems good.
oh, yes i cleared the code and cel went out for 2 days.

 

It would help to know what year XJ you have and what engine is in it.


You may want to fill in your Jeep data by opening your User CP, open Edit Your Details, then fill in the Jeep data under Additional Details.

 

ok i usually put that in each post.
2000 cher sport with 4.0 running great good oil pressure, smooth running,gutsy!
the prev owner left the connector partly plugged in and tapped. looks like a new cat and most new exhaust.
when i plugged it in fully it clicked solid and after 2-3 starts the actron showed good and showed voltage change on both sensors. this one #2 is on the new cat b4 the muffler.
had no cel for 2 days.
what checks can i make with a volt/ohm meter?, others?

 

Here's some diagnostic data pertaining to P0138:


P0138-1/2 O2 SENSOR SHORTED TO VOLTAGE


When Monitored: With battery voltage greater than 10.4 volts, engine running for more than 4 minutes and coolant temperature above 180°F.
Set Condition: The oxygen sensor voltage is above 1.5 volts.


POSSIBLE CAUSES


INTERMITTENT CONDITION


O2 SENSOR OPERATION


O2 SENSOR SIGNAL SHORTED TO VOLTAGE


O2 SENSOR SIGNAL CIRCUIT SHORTED TO O2 HEATER RELAY OUTPUT CIRCUIT


O2 SENSOR SIGNAL OPEN


O2 SENSOR GROUND CIRCUIT OPEN


PCM

 

made all ohmmeter tests i could. nothing seems missing. cleared codes reading data o2 1 volts vary. o2 2 volts read steady 1.00, no change.
no codes show,??ist it the o2 sensor? seems to ez looks new with new cat

heater reads apx 8 ohms, o2 should workwithout heater? i did not measure any volts.
what would make o2 sensor read exactly 1.00?? dead?

found this in an earlier o2 discussion..

mine is stuck. for a while 2 days ago it varied as it should. might need to throw $60 at it.
will check once more later.

 

id love a final expert opinion on this b4 ti throw money at it.
if i decide to change it will a muffler shop be able to get it out? i dont think i can.

 

If you are going to replace the downstream O2S, replace the upstream O2S as well. The PCM has issues with an old upstream with a new downstream and it may trigger a CEL because of it.


Use only NTK Oxygen sensors.

 

i cleared it and its been ok till about 4 hr on/off driving. o2 2 goes just above 1.2 on occassion and it lite the check engine but shows no codes?
otherwise its below 1.0.

 

Do you know what brand O2S' are currently installed?


For some reason the PCM does not like Bosch O2S' NGK are the original factory brand and should be used.

 

no idea, cat looks new but close look the o2 looks old, rusted in.
i never pulled one. pix from other post seat bracket doing floor work.

 

i sprayed it few days,tried a o2 whench, then big pipe wrench, absolutly stuck. its in the cat. muffler shop?, torch?
will they wreck the cat?
need opinions..

 

The muffler shop will put a torch to it to get it red hot in order to get it out. Shouldn't hurt the CAT.

 

ok thanks much, going tomorrow.