High Flow Cat installed. P0136 Code [Archive] - GrandAmGT.com Forum

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slowbird
05-04-2007, 02:11 PM
I just got my Highflow cat installed...drove around for about an hour or two...went home...showered...got in the car to go to the GF's and I get a SES light.

Code reader says it's a:
P0136: O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)

When we installed the cat we disconnected the O2 Sensor from the harness. But I have the MMS PCM...

Can anyone help me out with this?

The Code won't effect performance will it?

Thanks.

Sprucegagt
05-04-2007, 02:36 PM
It shouldn't but no one knows for sure. Bad thing is its letting the PCM think the converter is not doing its job. So it may very well run at reduced timing.

Did you ask MMS stop reporting the DTCs for the rear O2 sensor?

slowbird
05-04-2007, 02:48 PM
From an E-mail between Milzy and I:
Removing the rear O2 dtc's allows the customer to install a high-flow cat
or delete the cat without a SES light. The sensor can be removed.

it's part of the Milzy PCM package I got.

Is the P0136 code due to the Missing rear 02 sensor?

angrysk8r
05-04-2007, 03:15 PM
I have the MMS PCM and I am running without the rear O2 sensor in. It hasn't thrown a code yet.

slowbird
05-04-2007, 03:21 PM
I think I hear a small leak near the new cat.

...could that throw the code?

gectek
05-04-2007, 07:22 PM
yes that would throw the code and no that code will do nothing to the performance of the vehicle. those rear O2 sensor codes are for CAT efficiency and sensor effeciency only, there is nothing else that sensor effects. the upstream yes, but downstream...no. and yah an air leak would cause the sensor to read more O2 than what is put out by the engine, and throw a code

he didnt program the PCM right

slowbird
05-04-2007, 09:40 PM
I'll get the Cat/leak fixed tomorrow. If the Code doesn't pop up again, then I'm happy.

If not then I need to talk to Milzy.

ihatemygrandamg
05-05-2007, 12:36 AM
Matt your cars a pos...lol you know im j/k

How bad is the leak? What kind of cat do you have? Ive got the magnaflow 94035 on mt z24 which is fine,but my sh***y pacesetter header leaks alot.

Does your car seem to be running rich? Im thinking the o2 just might be bad or maybe the threads got stripped on it; or its just that milzy skipped out on your pcm. I had his basic tune as well but never got an aftermarket cat so idk.Maybe try disconnecting your battery overnight or something?

Sprucegagt
05-05-2007, 02:18 AM
I'll get the Cat/leak fixed tomorrow. If the Code doesn't pop up again, then I'm happy.

If not then I need to talk to Milzy.

Just an FYI, but that code will pop up again with no rear O2 sensor.

Sprucegagt
05-05-2007, 02:19 AM
yes that would throw the code and no that code will do nothing to the performance of the vehicle. those rear O2 sensor codes are for CAT efficiency and sensor effeciency only, there is nothing else that sensor effects. the upstream yes, but downstream...no. and yah an air leak would cause the sensor to read more O2 than what is put out by the engine, and throw a code

he didnt program the PCM right

Okay, you sound confident that you know what is going on with the rear O2 sensor. Got any info to backup your confidence?

gectek
05-05-2007, 11:29 AM
P0140

CIRCUIT DESCRIPTION
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference, or bias, voltage of about 450 mV . The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once in Closed Loop. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature, and provide an accurate voltage signal. The HO2S 2 is used for post catalyst monitoring. This DTC will set if the HO2S 1 voltage remains at or near the bias voltage amount.


i can go on if you want

slowbird
05-05-2007, 09:29 PM
When I clear the Code I can drive for hours and the code will NOT come up. It maybe comes up after a 100 or so km's.

I checked for leaks and there are none.

The exhaust shop said that there may be a leak from the Gasket between the Exhaust manifold and the downpipe. He can't see or feel any leak, but it may happem when the engine is under load and the exhaust pipes are hot.

I'm still getting the code: P0136: O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)

Is the "Bank 1 Sensor 2" definitley the Post-Cat O2 sensor?

I guess either the PCM wasn't programmed properly to get rid of that code, or there may be another issue.

I'm thinking I'll need to by an 02 Sim and install it. If the SES light never comes back I know my PCM wasn't done properly...if the code doesn't go away it may be the odd downpipe leak.

Suggestions/opinions?

slowbird
05-05-2007, 09:33 PM
More INFO:

It's a 2.5" Dynomax Cat.

The car runs very well. No issues. With the SES light I went to the track and ran a 14.9@91mph and had no issues with performance.

The exhaust seems clean.

Sprucegagt
05-05-2007, 11:45 PM
i can go on if you want

You only explained the code and nothing there indicates if you will have a performance decrease or not. Again without knowing how the PCM treats post cat O2 failures, you can't say it will not affect performance. Now wouldn't make just a tiny bit of sense that if the PCM noticed a deficient catalyic converter that it would make adjustments to prevent further damage.

Sprucegagt
05-05-2007, 11:52 PM
When I clear the Code I can drive for hours and the code will NOT come up. It maybe comes up after a 100 or so km's.

I checked for leaks and there are none.

The exhaust shop said that there may be a leak from the Gasket between the Exhaust manifold and the downpipe. He can't see or feel any leak, but it may happem when the engine is under load and the exhaust pipes are hot.

I'm still getting the code: P0136: O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)

Is the "Bank 1 Sensor 2" definitley the Post-Cat O2 sensor?

I guess either the PCM wasn't programmed properly to get rid of that code, or there may be another issue.

I'm thinking I'll need to by an 02 Sim and install it. If the SES light never comes back I know my PCM wasn't done properly...if the code doesn't go away it may be the odd downpipe leak.

Suggestions/opinions?

If the PCM was supposed to come with the rear O2 sensor codes deleted then it wasn't programmed correctly. I would send it back and have Milzy fix it unless you like looking at an SES light. You will not need an O2 sim if the PCM was programmed right.

gectek
05-06-2007, 12:41 AM
no, and i would have given more info but i am looking through my books right now for it. it is a catalyst efficiency monitor, nothing more. i can give scan tool data when i get my car up and running also...but ill get the other stuff tomorrow

slowbird
05-08-2007, 12:43 PM
Update:

Milzy is shipping me another prgrammed PCM with all rear O2 codes deleted.

He said that in almost ever case the P0136 code doesn't need to be deleted...I guess in my case it does.

Milzy is being real cool and shipping me a new one and I'll ship him back the old one once the new PCM is in.