1997 Cherokee 4.0L O2 sensor replacements.

[Bilskirnir3124]

Hello all.

Recently my 1997 Cherokee 4.0L tripped it's check engine light again. It's nice of it to let me know that the bulb still works. The codes it was throwing were a P0135 and P0138. It's also throwing a P0441 and a P0463, but I don't really care too much about those two. It's the Evap Purge system and my fuel gauge. Those can wait. From what I've been able to read, the P0135 is for the upstream heater, and the P0138 is a voltage problem on both the upstream and downstream sensors. I'm going out today to switch to get some replacement fuses, clear the codes, and see if they return.

If they do return, the questions I have are 1) am I right in assuming that both sensors need to be replaced? 2) What O2 sensors are good ones? I see Bosch on RockAuto, I know they're reputable from my time with an old Volvo 240, but only a downsteam unit. There's also Delphi and Walker. I see the name NTK thrown around quite a bit online. 3) Is there any thing important I need to know about doing the job? Special tools? A specific torque spec I need to know? Some important technique I need to know about replacing the sensors. This would be my first time replacing an O2 sensor so I want to make sure that there's not something I don't understand about doing this job.

As always, thank you for the help.

 

[RCP Phx]

NTK is the go to sensor and they can be a pita at times. It may require a O2 sensor socket if you can't break it loose with a box end wrench.

 

[Bilskirnir3124]

NTK is the go to sensor and they can be a pita at times. It may require a O2 sensor socket if you can't break it loose with a box end wrench.

Thanks. I'll pick up an O2 sensor socket. to be on the safe side. I like having sockets for things less fear of rounding a head. I've been looking into the trouble codes, and it looks like I have a code from the upstream sensor (the P0135) and the downstream sensor (the P0138). Is that the case? Also do you know the part numbers for those sensors? NTK seems a little tricky to source.

 

[phydeaux33]

Thanks. I'll pick up an O2 sensor socket. to be on the safe side. I like having sockets for things less fear of rounding a head. I've been looking into the trouble codes, and it looks like I have a code from the upstream sensor (the P0135) and the downstream sensor (the P0138). Is that the case? Also do you know the part numbers for those sensors? NTK seems a little tricky to source.

NTK23099 downstream, NTK23151 upstream both are on backorder per NTK website. NTK23179 is listed as up and downstream and is available.