'07 Impreza WRX Rear O2 Sensor

Wasabs · 12-07-2020, 12:30 AM

I apologize in advance if this is in the wrong section!

Recently put the transmission and stock engine back into the car, along with stock downpipe/catalytic converters. Basically, everything is OEM. The rear O2 sensor (with a green wire sleeve) that connects to the second catalytic converter is too short and won't reach the connector that's next to the rear torque strut mount. I've googled and looked all over several forums but can't find the solution so I'm asking here. The wire is a solid three to four inches too short?? It's the OEM part and I can't figure out what I'm doing wrong.

Any help is severely appreciated and thank you in advance!

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Blktrax · 12-07-2020, 10:18 AM

It connects to the driver side of the tail shaft harness on the trans. A patch harness that goes from the bell housing down the top of the trans to the tail shaft. Part of the harness for the Neutral/Reverse switches.

Wasabs · 12-08-2020, 12:28 PM

Quote:

Originally Posted by Blktrax

It connects to the driver side of the tail shaft harness on the trans. A patch harness that goes from the bell housing down the top of the trans to the tail shaft. Part of the harness for the Neutral/Reverse switches.

I think I figured out the problem - when I swapped out my transmission, I left the old connector cable on there and the one I bought didn't have that specific cable on it. I just purchased the part from the local dealership:

24039AA165

is the part number in case anyone makes the same mistake I did! Will update on this thread once the part comes in.

Wasabs · 01-08-2021, 11:07 PM

The O2 Sensor Connector came in and I drove around for half an hour before my idle got rough, the RPM floated below 600 and jumped up past 1000, then back down to 600 etc. I didn't notice any oil leaks and thought there wasn't enough fluid or something. The red oil pressure light flickered and then my car died right at the entrance to an oil change place; they topped it off and I drove it home (I know, not my best idea, but it was ~5 miles). Mechanic said my oil smelled kind of sweet and suggested it was maybe a head gasket issue. I bought new gaskets and patiently awaited their arrival.

I replaced the motor oil again bc I like wasting money, made sure it was all at normal levels on a cold engine, and started the car (I mostly did this to check if I effed my engine up by possibly driving with not enough fluid. No metal in the pan. Good, I think!). It started just fine, no rough idle, no weird sounds or smoke. I drove to a car wash place just to get miles on the recently-disconnected battery so I could smog the car soon (I had tried smogging the car previously, but it didn't have enough miles after I changed the battery. It passed everything else!). I begin to pull out of the parking lot and the same flickering oil light came on. White smoke coming from the hood. I pop the hood and look for the cause and the smoke was coming from the power steering pump. I bought a new gasket and patiently awaited its arrival.

I thought maybe it was because I put too much tranny fluid or something (I accidentally did), but the fluid levels for everything else were normal. I don't think a power-steering pump leak would cause weird fluctuations in the motor oil pressure like that, nor too much tranny fluid, so I did some research and a thread on here referenced what seemed to be the same problem, and it was the OEM oil pickup failing. I bought a Moroso Oil Pickup and yadda yadda.

Fast forward to now, I pulled the oil pan off and noticed all of this:

The whole bottom portion of the engine where the oil sits, the baffle, and parts of the oil pickup were nice and crispy.
https://imgur.com/LJ1umMU
https://imgur.com/adAaRfT
https://imgur.com/njsfeg1

I took a closer look at the welds on the OEM oil pickup and didn't see any noticeable gaps or holes.
https://imgur.com/RQ1c3n7
https://imgur.com/wIWNcrs

The oil pan also had this cracked piece, so I ordered a new pan, too.
https://imgur.com/UDIrkse

My new Moroso Oil Pickup ready for installation:
https://imgur.com/vusFXob

The new pan is coming in next Wednesday and I was hoping for some insight to see if this project car is worth pursuing some more or if I'm a complete dunce and messed my car up beyond repair.

Elbert Bass · 01-10-2021, 02:10 PM

Have you put a real oil pressure gauge on the engine to see what the actual oil pressure is? I have seen older switches go bad and close at higher than specified pressure.
Have you had the oil pump off? If so did you check if the oil pump screws were loose? Did you replace the o-ring seal and reseal the oil pump?

Wasabs · 01-10-2021, 11:20 PM

Quote:

Originally Posted by Elbert Bass

Have you put a real oil pressure gauge on the engine to see what the actual oil pressure is? I have seen older switches go bad and close at higher than specified pressure.
Have you had the oil pump off? If so did you check if the oil pump screws were loose? Did you replace the o-ring seal and reseal the oil pump?

I have not put a real oil pressure gauge on it, yet! I'll do that this week, and check back here. I have also never had the oil pump off.

12-07-2020, 12:30 AM	#1
Wasabs Scooby Newbie Member#: 498292 Join Date: Feb 2019 Chapter/Region: SCIC Vehicle: 2007 Impreza WRX TR	'07 Impreza WRX Rear O2 Sensor I apologize in advance if this is in the wrong section! Recently put the transmission and stock engine back into the car, along with stock downpipe/catalytic converters. Basically, everything is OEM. The rear O2 sensor (with a green wire sleeve) that connects to the second catalytic converter is too short and won't reach the connector that's next to the rear torque strut mount. I've googled and looked all over several forums but can't find the solution so I'm asking here. The wire is a solid three to four inches too short?? It's the OEM part and I can't figure out what I'm doing wrong. Any help is severely appreciated and thank you in advance! * Registered users of the site do not see these ads.

01-08-2021, 11:07 PM	#4
Wasabs Scooby Newbie Member#: 498292 Join Date: Feb 2019 Chapter/Region: SCIC Vehicle: 2007 Impreza WRX TR	I require assistance :) The O2 Sensor Connector came in and I drove around for half an hour before my idle got rough, the RPM floated below 600 and jumped up past 1000, then back down to 600 etc. I didn't notice any oil leaks and thought there wasn't enough fluid or something. The red oil pressure light flickered and then my car died right at the entrance to an oil change place; they topped it off and I drove it home (I know, not my best idea, but it was ~5 miles). Mechanic said my oil smelled kind of sweet and suggested it was maybe a head gasket issue. I bought new gaskets and patiently awaited their arrival. I replaced the motor oil again bc I like wasting money, made sure it was all at normal levels on a cold engine, and started the car (I mostly did this to check if I effed my engine up by possibly driving with not enough fluid. No metal in the pan. Good, I think!). It started just fine, no rough idle, no weird sounds or smoke. I drove to a car wash place just to get miles on the recently-disconnected battery so I could smog the car soon (I had tried smogging the car previously, but it didn't have enough miles after I changed the battery. It passed everything else!). I begin to pull out of the parking lot and the same flickering oil light came on. White smoke coming from the hood. I pop the hood and look for the cause and the smoke was coming from the power steering pump. I bought a new gasket and patiently awaited its arrival. I thought maybe it was because I put too much tranny fluid or something (I accidentally did), but the fluid levels for everything else were normal. I don't think a power-steering pump leak would cause weird fluctuations in the motor oil pressure like that, nor too much tranny fluid, so I did some research and a thread on here referenced what seemed to be the same problem, and it was the OEM oil pickup failing. I bought a Moroso Oil Pickup and yadda yadda. Fast forward to now, I pulled the oil pan off and noticed all of this: The whole bottom portion of the engine where the oil sits, the baffle, and parts of the oil pickup were nice and crispy. https://imgur.com/LJ1umMU https://imgur.com/adAaRfT https://imgur.com/njsfeg1 I took a closer look at the welds on the OEM oil pickup and didn't see any noticeable gaps or holes. https://imgur.com/RQ1c3n7 https://imgur.com/wIWNcrs The oil pan also had this cracked piece, so I ordered a new pan, too. https://imgur.com/UDIrkse My new Moroso Oil Pickup ready for installation: https://imgur.com/vusFXob The new pan is coming in next Wednesday and I was hoping for some insight to see if this project car is worth pursuing some more or if I'm a complete dunce and messed my car up beyond repair.

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12-07-2020, 10:18 AM	#2
Blktrax Scooby Specialist Member#: 220971 Join Date: Aug 2009 Chapter/Region: South East Location: NC Vehicle: 2004 Impreza	It connects to the driver side of the tail shaft harness on the trans. A patch harness that goes from the bell housing down the top of the trans to the tail shaft. Part of the harness for the Neutral/Reverse switches.

01-10-2021, 02:10 PM	#5
Elbert Bass Scooby Specialist Member#: 283429 Join Date: May 2011 Chapter/Region: South East Location: Down yonder. Vehicle: 2016 Fuji Sunfire 03 Silver	Have you put a real oil pressure gauge on the engine to see what the actual oil pressure is? I have seen older switches go bad and close at higher than specified pressure. Have you had the oil pump off? If so did you check if the oil pump screws were loose? Did you replace the o-ring seal and reseal the oil pump?