O2 sensor - help please !!
Thread Starter
Instructor
Joined: Aug 2004
Posts: 154
Likes: 0
From: Peterborough, UK
O2 sensor - help please !!
I'll keep my fingers crossed a few of the more technical members are online this evening.
On my 964 C2, some clever mechanic chose at some point in the past to cut off the connector on the wiring loom that is used to connect to the O2 sensor, instead i have three wires each joined to the O2 sensor cable by spade connectors.
I have a major problem at the moment in that the car is perfect when its dry, and stalls / cuts out as soon as it is wet, and I'm advised its likely to be my O2 sensor which has seen better days.
If I purchase a new O2 sesnor, it will have nothing to plug into ( since my connector on the main loom is missing), so to confirm this is the source of the problem, and get mobile, I am advised the best course of action is to remove it from the equation. Again this is normally done by jumpering the connector, in its absence I have to join two wires.
Coming from the wiring loom of the car, I have two green wires and one brown, from the O2 sesnor itself I have two white and black, and they are connected as follows :-
02 Sensor === Wiring Loom
White = Green
White = Brown
Black = Green
Can anyone help by advising on which two wires I need to join to effectively tell the Car the 02 sensor is removed. I don't want to damage anything by connecting the wrong two wires. I assume knowing which to join, I would need to DME reset afterwards in order for the car to know of the change ???
Any help would be really, really appreciated !!!
Thanks in advance
Al
90 C2 Targa
On my 964 C2, some clever mechanic chose at some point in the past to cut off the connector on the wiring loom that is used to connect to the O2 sensor, instead i have three wires each joined to the O2 sensor cable by spade connectors.
I have a major problem at the moment in that the car is perfect when its dry, and stalls / cuts out as soon as it is wet, and I'm advised its likely to be my O2 sensor which has seen better days.
If I purchase a new O2 sesnor, it will have nothing to plug into ( since my connector on the main loom is missing), so to confirm this is the source of the problem, and get mobile, I am advised the best course of action is to remove it from the equation. Again this is normally done by jumpering the connector, in its absence I have to join two wires.
Coming from the wiring loom of the car, I have two green wires and one brown, from the O2 sesnor itself I have two white and black, and they are connected as follows :-
02 Sensor === Wiring Loom
White = Green
White = Brown
Black = Green
Can anyone help by advising on which two wires I need to join to effectively tell the Car the 02 sensor is removed. I don't want to damage anything by connecting the wrong two wires. I assume knowing which to join, I would need to DME reset afterwards in order for the car to know of the change ???
Any help would be really, really appreciated !!!
Thanks in advance
Al
90 C2 Targa
Instructor
Joined: Sep 2002
Posts: 136
Likes: 3
From: Maryland
I'm not sure about UK cars, but the US cars need the 02 sensor to get anything close to "ok" fuel mileage. I'd suggest getting a new connector and splicing it into the wire loom inside the engine compartment (away from most of the water and gunk) then you can attach the 02 sensor to the connector in the normal fashion.
carl.
carl.
Technical Specialist
Rennlist
Lifetime Member
Rennlist
Lifetime Member
Joined: May 2001
Posts: 5,865
Likes: 26
From: TX
Al,
We've seen instances where a non-Porsche/generic O2 sensor didn't have a cap on it, which allowed water to enter it. I would not disconnect the O2 sensor, rather, I'd install the right O2 sensor (sounds like a prior mechanic may have installed a generic 3 wire O2 sensor). Anyhow, for 1990, there is a brown wire which connects to junction 1 at the O2 sensor, a green/black wire to junction 2, and the third wire to junction 3 (it's not color coded in the wiring diagram for 1990, but a later year diagram shows that wire as a green wire). There is a plug coming out of the wiring loom shows as part 944.612.422.00 on the 91 and later wiring diagrams (don't often see part numbers on the wiring diagram). Why not get that part, hook your loom up correctly to the plug, get the right Porsche O2 sensor, and be done with it. Maybe someone can post a scan of the O2 sensor from Sheet 5 (bottom left corner) of the wiring diagram in the factory manual.
We've seen instances where a non-Porsche/generic O2 sensor didn't have a cap on it, which allowed water to enter it. I would not disconnect the O2 sensor, rather, I'd install the right O2 sensor (sounds like a prior mechanic may have installed a generic 3 wire O2 sensor). Anyhow, for 1990, there is a brown wire which connects to junction 1 at the O2 sensor, a green/black wire to junction 2, and the third wire to junction 3 (it's not color coded in the wiring diagram for 1990, but a later year diagram shows that wire as a green wire). There is a plug coming out of the wiring loom shows as part 944.612.422.00 on the 91 and later wiring diagrams (don't often see part numbers on the wiring diagram). Why not get that part, hook your loom up correctly to the plug, get the right Porsche O2 sensor, and be done with it. Maybe someone can post a scan of the O2 sensor from Sheet 5 (bottom left corner) of the wiring diagram in the factory manual.
Thread Starter
Instructor
Joined: Aug 2004
Posts: 154
Likes: 0
From: Peterborough, UK
Bill / Guys,
Thanks so much for your assistance, its greatly appreciated. I take your comments on board and my best solution is to replace the O2 sensor with an official Porsche one. I am keen to "prove" this is the issue, so ideally I want to jumper the connection first, check the problem goes away, and then order my new O2 sensor.
Can you advise which 2 connectors are joined to tell the system that the O2 sesnor has been bypassed ?
Thanks again
Al.
Thanks so much for your assistance, its greatly appreciated. I take your comments on board and my best solution is to replace the O2 sensor with an official Porsche one. I am keen to "prove" this is the issue, so ideally I want to jumper the connection first, check the problem goes away, and then order my new O2 sensor.
Can you advise which 2 connectors are joined to tell the system that the O2 sesnor has been bypassed ?
Thanks again
Al.
Race Car
Joined: Aug 2001
Posts: 4,922
Likes: 1
From: London, UK
Al
When my car was standard, JZ Machtech actually jumpered the DME itself to ignore the O2 sensor....as someone else has said, have a word with them. When I replaced my exhaust system a couple of years ago, they replaced my O2 sensor with an altitiude sensor and the aforementioned jumpering of the DME. I have no doubt that the car ran a little rich, but got decent fuel consumption and passed MOT no problem...
When my car was standard, JZ Machtech actually jumpered the DME itself to ignore the O2 sensor....as someone else has said, have a word with them. When I replaced my exhaust system a couple of years ago, they replaced my O2 sensor with an altitiude sensor and the aforementioned jumpering of the DME. I have no doubt that the car ran a little rich, but got decent fuel consumption and passed MOT no problem...
Thread Starter
Instructor
Joined: Aug 2004
Posts: 154
Likes: 0
From: Peterborough, UK
Thanks for all you help guys. I am going to order a new one, and in the meantime have disconnected the O2 sensor to confirm it is the source of the problem. For the record, if you want to jumper the O2 sensor from the main wiring harness, you join connectors 1 and 3 ( black and Green Wires).
THanks again
Al.
THanks again
Al.
Trending Topics
Drifting
Joined: Jul 2001
Posts: 2,298
Likes: 78
From: St. Louis
Not to hijack the thread, but I have a 4-wire O2 sensor I got for my S2 and it's just sitting here now looking like a project needed to be started. Are the sensors the same for the 1990 S2 and the 1991 C2? Any ideas on which wires fo where?
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