P0136 on '02 forester

[1-3-2-4]

My friend just drove by to check on how I was doing and also because he had a code the code reading was saying the code and circuit malfunction Bank 1 Sensor 1 if I remember right.. I know I went into live data and I only saw the rear o2 sensor.

 

the car has about 90K on it

 

bad sensor or really a circuit issue?

[Recian]

i dont see why you couldnt see the front O2 in the data list unless he had an older scanner. There are resistance checks you can run for the sensor's heater and circuit to make sure it's within order and the plugs are easy to access.

[1-3-2-4]

The scanner is new enough I guess that's why it was throwing the code?

[Recian]

In situations like this I usually hook up my Modus to get a second opinion kinda. It never hurts with OBD data to use a second scanner if something seems out of the ordinary. If the ECM isnt even displaying O2S1 i'd think something isnt right in the ECM. If it cant even display or monitor B1S1 then it will say uh oh and throw a code but i'd rather say it's in the 02 sensor because even if the sensor was disconnected it'd show default of 0.30v or 0.00v in live data depending on the vehicle. Im looking at it on Shopkey atm but unfortunately you have an A/F sensor (air fuel ratio) which runs a 2.500v reference instead of 0.0-0.9v. Theyre much more complex and generally throw other codes like P0A instead of P01 My wiring diagram just shows 5 wires and doesnt give me the internals or dimentions so i cant tell u which terminals to check. Unfortunately a/f sensors are an expensive guess too. I can give you ECM terminals to check tho. If wiring is ok it's either a ecm or sensor. These terminals should have continuity when checked with a volt/ohm meter.

 

02 terminal: 1 (red)connects to ECM B135 terminal: 19

02 terminal: 2 (yellow/red)connects to 02S2 terminal:2 and Main relay terminal: 4 Main relay is behind LH side of dash with 6 terminal connector.

02 terminal: 3 (green) connects to ECM B135 terminal: 6

02 terminal: 4 (white) connects to ECM B135 terminal: 7

02 terminal: 5 (brown/black) connects to ECM B134 terminal: 22, 23

02 terminal: 6 (black) connects to ECM B135 terminal: 20

 

You shouldnt mistake 22/23 on B134 with 22/23 on B135 since it says 18/22/23 arent used on B135

Edited April 29, 2012 by Recian

[Fairtax4me]

P0136 O2 Circuit Bank 1 Sensor 2, according to canobd2.com. This will be the after cat sensor on the passenger side bank.

 

By "no reading" do you mean that it did not show an O2s2 on the scanner at all, or did it show the sensor just at 0v?

 

Im looking at it on Shopkey atm but unfortunately you have an A/F sensor (air fuel ratio) which runs a 2.500v reference instead of 0.0-0.9v.

 

THIS is particularly interesting to me because there have been several occasions where people have reported O2 readings in the 2.5-3.5V range rather than the typical 0.1-1.0v range that people are expecting.

Having a reference feed to the sensor, does the sensor output reading still fluctuate by a 1 volt range above or near the reference voltage?

 

The above actually is a whole other can of worms, but as Recian said, check wiring to the sensor, it's possible one of the wires is cut or shorted, or there is a bad connection in one of the harness connectors along the way.

[Recian]

Yea those 3v sensors are air flow ratio not o2 sensors. Theyre used pre cat in newer cars and theyre very expensive but not commonly failing either. If ur code number is for the rear sensor then it adds up

[njdrsubaru]

i had that code recently... i changed the rear o2 sensor and and no codes so far

[1-3-2-4]

is wife is nabbing him and I guess he wants to do it this Sunday, I'm going to guess it takes less effort to get off then the front? Her car is pretty much rust free under the car and has about 92K.

[1-3-2-4]

Changed out the rear sensor today pulled the battery cable CEL is still showing however I did not have my code reader with me but I would think the code would go away after a reset? Or for something like that I need to reset it with the code reader?

[Caboobaroo]

The code is probably hard set into the ECU. Would need to be cleared properly. IIRC, that code comes on after two running cycles. Also check the harness on top of the transmission for an issue. Could come down to an ECU issue if everything else checks out. I can look at a flow chart tomorrow at work for more ideas.

[1-3-2-4]

I told him the next time I would be over the house is saturday but he was in a rush so it was crazy having to shuffle all the cars.

[1-3-2-4]

he told me the CEL went out for the 02 sensor now but going to check again this weekend just to be sure.

[1-3-2-4]

The light went out on it's own but I was back at the car today and did a rescan and well I will just let the video speak for it's self.