So I had a check engine light from not having a cat (according to the previous owner) so I installed a 42dd o2 sensor spacer and cleared the existing code
The code was P0420 which is Catalyst System Efficiency Below Threshold (Bank 1) So I went ahead and cleared it, a day or so later the CEL came back and I ran the reader again (I dont have a vag-com and I am just using a normal reader) and it came up with 2 new codes
P0138 - O2 Oxygen Sensor Circuit High Voltage (Bank1, Sensor2)
So I am guessing I need to replace the rear o2 sensor? I can just get one of the Bosch ones right? I just unscrew the sensor, unplug it from the box (which is located near the rear o2 sensor right?) and plug it back in and erase the code?
I dont think I need to adjust the spacer at all because the spacer is about as far as it can get...I was only able to screw it on half a turn (which was tough in itself) and it is pretty snug on the pipe. It is also oriented so that the o2 sensor faces the rear of the car.
i feel your pain. i have to tweek mine to get just right. im going to be installing a high flow cat. soon so it should help. i just keep clearing mine, comes back after a few miles of driving. i think mine is being thrown due to the o2 sensor being on the bottom, thus letting build up get onto it. i just have to spin the test pipe.
im running unitronic stage 2. i would just replace 1 o2 sensor first. it might be possible that you have it spaceed out too far and it is barely getting a reading.
Which one do I replace then the pre or post cat? Would having it too far actually give a code because I really cannot adjust it any further...the spacer only screws into my pipe a half turn and I cannot turn it anymore than that :/
Would it be cheaper to just go to a shop and have the o2 sensors replaced as opposed to buying the sensors ($130 for the rear one for example) and replacing them myself? I'm assuming they would use bosch sensors. How much quicker do they burn up compared to the oem ones?
Assuming I am understanding this correctly you are throwing a CEL because of the o2 censor. I don't know if it would be the same code as one that would show if you didn't have a catalytic converter installed. Anyway I have unitronic stage 2 reflash and they told me that the car will never throw a CEL for a catalytic converter or lack of. They said if it ever does I could bring it to them and they will fix it. I am putting on a new exhaust this month so I don't know yet so I will find out after I remove my cat if it throws a CEL. If I read correctly you also have unitronics. You should talk to the place that did it for you.
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