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2003 Front O2 Sensor Wiring Pin Out


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8 replies to this topic

#1 lmdew

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Posted 17 March 2014 - 09:19 PM

Anyone have the wiring pin out for the front O2 sensor for a 2003 SOHC 2.5 Legacy Outback.

 

Red              Y/R

 

 

White           Yellow

 

 

That is the wires I have looking at the front of the plug but all of the wires were pulled out when I go the car.

 

Thanks 



#2 Fairtax4me

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Posted 17 March 2014 - 09:53 PM

According to FSM for 03 Legacy.
Back view of the harness side connector.
Lock tab on top

2 1
4 3

2 = Red
1 = white
4 = Y/R
3 = Green

Y/R is 12v from the fuse box for the heater.
Green is heater ground. Should show less than 1.0v with key On.
White is Sensor bias voltage ~ 2.0-2.25v with engine idling.
Red is sensor bias voltage ~ 1.75-2.0v engine idling.

#3 lmdew

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Posted 18 March 2014 - 05:54 AM

Great THANKS.  

 

Got to get the wires in the right spot.



#4 lmdew

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Posted 08 May 2014 - 01:44 PM

Bump, can some one verify the FSM

Here is what I have:

 

Anyone have the wiring pin out for the front O2 sensor for a 2003 SOHC 2.5 Legacy Outback.

 

Red              Y/R

 

 

White           Yellow

 

 

That is the wires I have looking at the front of the plug but all of the wires were pulled out when I go the car.



#5 lmdew

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Posted 18 May 2014 - 09:44 PM

Finally had a bit of time to re-pin and check voltages, looks like I'm missing the ground for the heater.

 

Key On

 

Red- 1.8 volts              White - 2.1 volts

 

 

Y/R 12.11 volts          Yellow (with the sensor disconnected it was reading 2.7 volts, once the sensor was plugged in and I back probed it it read 12.11 volts) Looking at the wiring it looks like this ground is in the ECU.  The ECU is throwing P0130.

 

I checked the old and new sensor resistance on the heater circuit and it only showed 1.6 ohms.  Subaru and a new Bosch Sensor.



#6 Fairtax4me

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Posted 18 May 2014 - 10:57 PM

That's no good. Possible the heater 12v feed wire touched the ground wire when it got disconnected and cooked the ground circuit in the ECU.
Probably want to check voltage at the pin in the ECU, and make sure there's no crud in the ECU connector.
I don't think the front sensor has any other connectors between it and the ECU, so not much chance of a poor connection unless its at the sensor connector.

#7 lmdew

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Posted 20 May 2014 - 06:46 PM

Anyone have the pinout for the ECU connectors?

 

ECU #'s

4C

22611 AH05E

JA18000 RK3 3304

 

Front O2 sensor is missing the ground, provide by the ecu.

 

ECU has 4 plugs on it.

 

Thanks



#8 Fairtax4me

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Posted 20 May 2014 - 07:20 PM

You need the heater ground right?

B137 pin 9
B137 is the largest connector.
There is an open slot in the top row. Pin 9 is the very last pin on the opposite end (still top row).

#9 lmdew

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Posted 20 May 2014 - 09:18 PM

Thanks, I checked it but there is no yellow wire in that row of B137

 

From the back of the connector the

 

Left side the first pin is pink with green stripe

 

The other end of the connector, right side close to the second connector in the row is a green wire.

 

the connector is 

p p I p p I x x I p p I p p

 

so 8 pins, only 7 wires.

 

The diagram I have shows the yellow wire going in on pin 17

It also shows a connection to a pink wire which goes in on pin 1

 

Not sure I'm trusting the Mitchell repair information i got.

 

do you show a wire color for pin 9?

Thanks Larry






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