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Discussion Starter #1
Hey!
2001.5 VW Passsat AWM 1.8t FWD, Sedan, Automatic Transmission

Last week I put on a 3" 034 Test pipe with a spacer on the second o2 sensor hoping that it will not throw CEL. Well, it did went on which I kinda expected, but I did not scan the codes. Over the weekend I purchased a Stage 2 Unitronic Performance Software. They were promising that their software takes care of the o2 emission CEL's which I was really happy about. After the first start the CEL was off but on my way home it went on. Surprised I scanned the codes and I got:

P0030 >>---> P0030 Volkswagen HO2S Heater Control Circuit Bank 1 Sensor 1 OBDII Engine Light Trouble Code | Engine-Codes.com
P0135 >>---> P0135 Volkswagen HO2S11 Sensor Heater Circuit OBDII Engine Light Trouble Code | Engine-Codes.com
P0136 >>---> P0136 Volkswagen HO2S12 Sensor Range/Performance Condition OBDII Engine Light Trouble Code | Engine-Codes.com
P0140 >>---> P0140 Volkswagen HO2S12 Sensor Circuit No Activity Detected OBDII Engine Light Trouble Code | Engine-Codes.com
in this exact order.

I checked the code and the first two seem to be responsible for the first o2 sensor (the way i understand the descriptions). I called Unitronic and asked whether it's possible that something went wrong while installing the flash and the tech dude told me that the only code that they get rid of is P0420 (which pretty much means faulty cat, so test pipe would throw it too, which in this mater would mean that they did get rid of it).
Now, looking at the codes could that mean that there is something wrong with the first sensor? Could I have damaged it during the installation? I know that these are still the first sensors on this car, so they are really old. Also when I was taking off the first sensor I squeezed the top metal part of the sensor with pliers, cuz I had difficulties untwisting it, so it is slightly bent in. :angel:
 

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Yes, you damaged the first sensor and will need to replace it. The Bosch 17351 aftermarket unit is an acceptable (and much cheaper) replacement vs. the OEM version. ($82 today at Amazon.)

FYI, the trick to removing O2 sensors is penetrating oil (NOT WD-40), the proper tool, and heat. Mine didn't want to budge without penetrating oil, and took minimal effort with it. (Squirt penetrating oil (I used P'Blaster, but Kroil or Liquid Wrench would be fine), wait a few minutes, crank, wait for the oil to start smoking, turn off the engine, soak it with a little more oil, wait a couple minutes, and it'll come right out.)
 

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Discussion Starter #4
ok so update
replaced the sensor and all the codes were gone till today
got the check engine light again and scanned the code
this time it's only p0136 which would mean that the first sensor was broken and needed to be replaced
does that mean that now I have to replace the second one too? :bowdown::puke:
 

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ok so update
replaced the sensor and all the codes were gone till today
got the check engine light again and scanned the code
this time it's only p0136 which would mean that the first sensor was broken and needed to be replaced
does that mean that now I have to replace the second one too? :bowdown::puke:
The code points to bank 1 sensor 2. It is not getting any signal from the rear sensor meaning it is either defective or there is a break in the wiring. Check the wiring for breaks or shorts or replace the sensor.
 

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Well, what difference does the second sensor make? After all, your car has a "test pipe" and isn't being used on public roads, (in flagrant violation of a whole pile of state and federal pollution-control laws) right? Isn't that why it's called a "test" pipe? Surely you are only tracking it! A code for the 2nd sensor won't affect the mix.

The death of both your O2 sensors could be the gods of karmic justice punishing you for removing the cat.
 

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Discussion Starter #9
yeah i don't really care that i have the code for the second sensor but i'm due for inspectioon next month. yes, i wouldn't pas the state inspection at mvc but i would at some private place which is why im trying to figure this thing out ;)

and yes, TOM, 2 threads is too much but the other one is like 6 years old! :D
 

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I would think that a good flash would have disabled the second O2 sensor?
For some meanings of "good". Some software flashes have the option available, but as far as i know, even if it is, you have to specify it. Disabling a warning that a Federally-required emission device isn't working is of slightly questionable legality.
 

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Discussion Starter #13
so, after few days of driving with the code on, it disappeared. i scanned with OBD just to make sure and it's not popping off. so i guess i'm good with it for now! :D
 
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