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Jeep Codes

Discussion in 'Jeeps' started by MickiRig1, Aug 28, 2008.

  1. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    A friend of mine is getting codes from auto-zone's scanner. They do not come up with an explanation of the codes. Just comes up with PO31 and PO51. It's a 2004 Cherokee - Laredo with the 4.0L. It's just had the O2 sensors replaced and the codes cleared these popped up a week later.
     
  2. festerw

    festerw Senior Member
    Messages: 986

  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Codes aren't correct Micki, not enough digits. Did you mean P0031 and P0051? Those are both O2 heater related codes. Any other codes?

    BTW...All codes (history or pending or OEM specific) may not show up with one of those cheapie Autozone code readers.
     
  4. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Thanks B& B and FesterW.
    It's a lady at work that has the Jeep. Midas got her for the O2 sensors. Looks like it will go back to them!
     
  5. Donny O.

    Donny O. Senior Member
    Messages: 410

    if it is for O2 heaters those would be the after cat O2 sensors....unless things have changesd since 96 and it is completely different than my car!! they have pre heaters in them because after the cat the exhaust is not as hot and they need to get to temp quick. basicaly the after cat sensors are jsut there to say if the cat is working or not....it does nothing with tuning or how anything runs......just sets a light if the cat isn't working.....or if the sensor itself is bad. what i'm saying is it can be ran like that with no harm done other than an anoying light!!
     
  6. festerw

    festerw Senior Member
    Messages: 986

    ^ or it is possible that they used some cheap universal O2 sensors without the heaters.
     
  7. Donny O.

    Donny O. Senior Member
    Messages: 410

    ya just cant trust anyone anymore!!
     
  8. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    In our area we have emissions testing. If the check engine light is on they will not even hook it up. I would bet the computer looks for trouble codes and when they were last cleared. I was told you have to have 10 start / drive / stop cycles and 50 miles driven after the codes are cleared to pass.
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The pre-cat (primary) O2's are heated as well. Been mandatory since '96. :)
     
  10. Donny O.

    Donny O. Senior Member
    Messages: 410

    well there ya have it....I have been educated!!