My 1998 Pathfinder is giving me DTC P0161 for a downstream O2 sensor. Around 2020 I replaced both upstream sensors (no code-just maintenance) but did not replace the downstream sensors because it seemed difficult to snake the cables from the CATS up through to the top of the engine. Now I have a code for downstream O2 sensor and would like to replace them both but I have some questions.
What is the best way to replace these sensors? It looks I will need to send them up through the engine to plug them in from the CATS. My only thought on how to do this is to unhook the sensor from the CAT, install the new sensor into the CAT, tie together the new and old sensors and somehow pull the plug up through the engine and finish plugging the new one in.
Am I overthinking/missing something? Any tips are appreciated.
Also looking at Rockauto for the parts I found the two Downstream sensors (13257 downstream left) and 13264 (downstream right). One of them mentions it is for an auto transmission, the other does not mention it. Can I assume they are both for automatic?
Thank you!
1998 Pathfinder downstream O2 sensors
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Alibireason
- Posts: 94
- Joined: Sat Jan 16, 2021 2:22 pm
- Car: 1998 Nissan Pathfinder SE
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mdmellott
- Posts: 1269
- Joined: Mon Sep 02, 2019 3:32 pm
- Car: '13 Kia Soul+ 2.0L AT
'02 Pathfinder SE 3.5L AT P/4WD - Location: SF Bay Area, CA
Re: 1998 Pathfinder downstream O2 sensors
Unplug the sensors. Tie a 3ft long string to the plug. Tie the other end of the string to the O2 sensor harness connector, or just about anywhere inside the engine bay. Pull the O2 sensor wire and plug out from below. Remove the O2 sensor from the exhaust. Install the new O2 sensor. Cut the string off of the old plug and tie it onto the new plug. Pull it up into the engine bay and plug it in.
The only tricky part is getting the wire retainer clips, closest to the O2 sensors, pushed into the tiny holes that hold them in place. The other clips are easily accessible and visible but the ones closest to the sensors are nearly impossible to get at. I gave up trying on the passenger side and almost gave up on the driver side. No worries though. They are not that critical. Someone with very small and skinny hands would be able to manage it easy.
The only tricky part is getting the wire retainer clips, closest to the O2 sensors, pushed into the tiny holes that hold them in place. The other clips are easily accessible and visible but the ones closest to the sensors are nearly impossible to get at. I gave up trying on the passenger side and almost gave up on the driver side. No worries though. They are not that critical. Someone with very small and skinny hands would be able to manage it easy.
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Alibireason
- Posts: 94
- Joined: Sat Jan 16, 2021 2:22 pm
- Car: 1998 Nissan Pathfinder SE
Re: 1998 Pathfinder downstream O2 sensors
Sorry it took so long to reply. I had put this one on the back burner while working out the alternator/starter problems, which I appreciate your help on as well. I'll update you when I get I am able to get this one addressed. Thank you MD!