My 04 keeps throwing the Replace 02 sensor.......OK, but how do I tell which of the two 02 sensors to replace ?

 

The code should tell you upstream (before cat) or downstream (after cat).

 

Code reader should give you bank # (bank 1, bank 2) If you've got a Bentley's, check the code listings in the back. They'll clue you in.

 

from my Innova Code reader.

I get a P0 136 (Bank 1, Sensor 2) 02 Sensor Circuit Malfunction
is this the down stream 02 sensor ?


Looking this up online as a BMW specific code I get:
P1136 O2 Sensor Heater Circuit High Voltage (Bank 1 Sensor 1) which seems to conflict with the P1 136 generic code listing

and a

P2 270 no such listing in my code list

Anyone have ideas on the P2 270 code ?

Looking online I find a Generic code listing
P2270 O2 Sensor Signal Stuck Lean
P2270 O2 Sensor Signal Stuck Lean (Bank 1 Sensor 2)


Suggestions would be VERY welcome

 

ttt

 

I think I can help you diagnose your problem but I am a little confused. Please repeat only the codes you are getting from your scanner. I need all of them if more that one, also i need to know if this is an S or not. Thanks.

 

In the mean time here is the meaning of code P0136: open circuit on the post catalytic oxygen sensor. The voltage remains low and never goes above the switch point of .45vdv....this can be caused by an open fuse for the o2 heater...a cold sensor will report a constant low voltage.

The meaning of p2270: A constant low voltage on the post catalytic sensor (same sensor as above).

The ECM determines this by commanding a rich fuel mixture....if the voltage does not go high after 7 secs....this error is flagged. If this condition occurs for two consecutive drive cycles...the SES light is illuminated.

I do not believe the problem is a blow fuse, since the same 15amp fuse (F03) is used for both front and rear o2 heaters...and you are not getting any errors for the front o2.

I do not think the constant low voltage is caused by an exhaust leak in close proximity to the post o2 since the ECU is reporting an open condition.

Conclusion: A poor connection in the o2 connector or wiring, simulating an open circuit; or an open internal to the o2 itself.

pardon the long winded response, but this may help others that have the same problem. Please advise on how you make out and good luck!

 

Thanks,

Two codes when the SES light is ON

from my Innova Code reader.

I get a
P0 136 (Bank 1, Sensor 2) 02 Sensor Circuit Malfunction
P2 270 no such listing in my code list

The SES light will stay on for a few days then go out for a few, then back on.
I got a new 02 sensor, so I guess I will replace the 02 down stream from the CAT.........correct ?

Thanks,

JIm

 

the codes relate to the o2 after the cat.

 

Thanks to all,

Now to get the bugger out.......the last 02 sensor I did on my Talon almost broke my arm

 

http://www.obd-codes.com/p0136