Threw a Code: po138 -

2nd Gen Ram Tech 1994-2001 Rams: This section is for TECHNICAL discussions only, that involve the 1994 through 2001 Rams. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.

Threw a Code: po138

Thread Tools Search this Thread
Old 12-18-2005, 09:32 PM
SLT360 SLT360 is offline
Thread Starter
Join Date: Dec 2005
Posts: 14
Default Threw a Code: po138

My Baby, 99 SLT 5.9 4x4 1500 threw the code p0138....Basicly rear oxygen sensor high voltage. After searching the forum i found a few old threads dealing with either cleaning it or preferable replaceing with a mopar or similar sensor. 2nd time its thrown it in the past week and i have cleared it both times.

1. Will running for a week with this damage anything?
2. What EXACTLY does this mean.....high voltage to a sensor doesnt really mean anything to me?
3. Affect gas mileage....not that it matters with these babies
Reply With Quote
Old 12-18-2005, 10:54 PM
Socha_62 Socha_62 is offline
Record Breaker
Join Date: Oct 2004
Location: Gaylord, MI
Posts: 2,456
Default RE: Threw a Code: po138

It won't hurt anything running it like that. If its the rear sensor its either actually bad itself, or your cat isn't working right.

High voltage just means its getting a reading from it out of the normal operating range. It gets this higher reading because of what I just said, sensors bad or cat isn't working right
Reply With Quote
Old 12-18-2005, 11:23 PM
shott8283 shott8283 is offline
Join Date: May 2004
Location: Bett-neee
Posts: 3,810
Default RE: Threw a Code: po138

you can try taking the aft o2 sensor out and cleaning it really good... becarefull though... they are delicate..just wipe it down and maybe spray it with some carb cleaner... LIGHTLEY spray it and wipe it down and let it airdry overnight.... make sure its screwed back in nice and snug and hook it make up..also make sure the plug is clean too..on both ends... make sure theres no dust... but with that code it prolyl means you need a new one... too high voltage.. prolly shorted out or malfuntioned... when i went to change mine out .. it cost me 120 bux for a brand new mopar one... reason being is that if you get the universal ones..they tend to not work right and throw codes and **** you off... i hate seeing my CEL on... if you clean your original one.. itll help to blow it out with some compressed air..also if you put the new one in and see if the CEL comes back on...if it doesnt..throw the old one back in and see if it comes back... good way to make sure you spent 120 or so bones good...
Reply With Quote
Old 12-18-2005, 11:59 PM
SLT360 SLT360 is offline
Thread Starter
Join Date: Dec 2005
Posts: 14
Default RE: Threw a Code: po138

thanx, i dug up a old troubleshooting book and it said the exact same thing you guys did. so i think ill just replace it this weekend....i assume i have to go through a dealership to get a mopar sensor?
Reply With Quote
Old 12-19-2005, 12:29 AM
bamory bamory is offline
Join Date: Feb 2005
Location: OHIO
Posts: 678
Default RE: Threw a Code: po138

Mine threw the same code, I took it out and used Carb cleaner and a toothbrush to clean it (inside the grooves were carboned up), that was 15,000 miles ago, not saying you will get that much outta yours, but it can keep the 60.00 in your pocket longer
Reply With Quote
Old 11-13-2011, 06:57 PM
larryb09 larryb09 is offline
Registered User
Join Date: Nov 2011
Posts: 2

what would cause my 5.2 liter '98 ram 1500 4x4 to idle high up and down on start up and while driving?
Reply With Quote
Old 11-13-2011, 07:27 PM
HeyYou's Avatar
HeyYou HeyYou is offline
Super Moderator
Join Date: Apr 2010
Vehicle: 1996 Dodge Ram 2500
Location: Adrian, MI
Posts: 40,527

Bad IAC motor, or, failing TPS, or Failing O2. Does it always do it? only when warm? Just till it warms up a bit??
Reply With Quote
Old 11-14-2011, 01:34 PM
larryb09 larryb09 is offline
Registered User
Join Date: Nov 2011
Posts: 2

Thank you Hey You! These are what I was kind of leaning towards.
Reply With Quote
Old 10-30-2012, 10:35 AM
hemi 2500 hemi 2500 is offline
Registered User
Join Date: Sep 2011
Posts: 3

so does anyone know what bank 1 sensor 2 is on a ram 2500 2003, it didnt say upstream or downstream .
Reply With Quote
Old 10-30-2012, 11:19 AM
drewactual's Avatar
drewactual drewactual is offline
Join Date: Aug 2010
Vehicle: '02 1500 5.9L Magnum
Location: Cape Carteret NC
Posts: 2,698

bank one- drivers side four cylinders.. sensor two- behind the first one, aka 'downwind'..

if you're running a fed emissions rig, sensor 2 is the downwind, period (for both sides)
Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Shaky Truck trevorrawson 3rd Gen Dakota 17 10-26-2015 04:55 PM
[3rd Gen : 96-00]: 2000 Caravan Shift Stutter jdb255 Dodge Caravan 2 09-21-2015 12:15 PM
[4th Gen : 01-07]: What should I save? 2002caravan Dodge Caravan 2 09-15-2015 09:00 PM
Another ABS/brake light thread Operator13061 2nd Gen Ram Tech 2 08-20-2015 09:59 PM
1999 dodge 1500 vacuum lines Ryan E Meadows 2nd Gen Ram Tech 6 08-12-2015 11:32 AM

2004, 2005, car, caravan, code, codes, dakota, dodge, high, o2, po138, ram, sensors, stratus, troubleshooting, voltage

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

All times are GMT -4. The time now is 12:19 PM.