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Discussion Starter · #1 ·
I have a 2004 G and cannot figure out the problem. The car is basically 50% power and running very rough/lean. I recently received an O2 sensor error so I replaced the O2 sensor but something is still wrong. If I clear the error codes with an OBD scanner they come back within 10 minutes of the car idling. The error codes are:
  • P1426(Unknown Diagnostic Trouble Code)
  • P2195(O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1)

From reading extensively in forums and whatnot, I decided to replace the Thermo junction box AND both cat temp sensors(bought OEM kit from AMH parts(thanks Glen!)). I was sure that this would fix it but same limp engine and error codes. I am not sure what else to do and I am hoping someone can suggest something? I have disconnected the batter several times to "reset" the ecu. For what its worth, all of the Coilpacks and spark plugs are less than 1 year old....
Some things I was wondering are:
1. Even though the Bank1/Sensor1 O2 plug is brand new, is there anyway to "test" that it is in fact working or not working(even though it is brand new)?
2. The car was outside for 3 days while my garage was being epoxied, and we had a ton of rain. I am not sure if this is related to something with moisture? It has been over 30 days since then and sitting in my dry garage.
3. I checked all the fuses behind the passenger seat, nothing is blown. Not sure if there is anything else I should check?

NOTE: When reading the engine diagnostics while it is running, I noticed that the voltage for Bank 1 Sensor 1 and Sensor 2 is very low. Maybe this is because bank 1 is "disabled" due to whatever issue exists?

I have an appointment with my local lambo dealer but they are so booked that it is 1 month away and I am hoping to fix it myself before then. Hopefully the community can guide me in the right direction. Thanks for any input!
 

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Either one of your catalytic converters has a problem internally, or you have a bad O2 sensor giving you a false reading, or you have a bad Cat temp sensor giving you a false reading. These things are garbage and are known to fail or fill up with rust. Check it all.

P1426 on these cars is a cat temp warning. It triggers when a temp greater than 200C is detected for longer than a minute. Every single part mentioned is known to commonly fail on these cars. OEM cats are pretty much 100% failure rate. This car has more "100% failure rate" items than anything I've ever owned.
 

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Discussion Starter · #3 ·
Either one of your catalytic converters has a problem internally, or you have a bad O2 sensor giving you a false reading, or you have a bad Cat temp sensor giving you a false reading. These things are garbage and are known to fail or fill up with rust. Check it all.

P1426 on these cars is a cat temp warning. It triggers when a temp greater than 200C is detected for longer than a minute. Every single part mentioned is known to commonly fail on these cars. OEM cats are pretty much 100% failure rate. This car has more "100% failure rate" items than anything I've ever owned.
Thanks for the reply. I don't have any cats on the car so it wouldn't be those. The O2 sensor giving the error is a brand new OEM sensor(I suppose it could still be bad?). Both Cat Temp sensors were replaced because I thought it could be them as well, but didn't help. So If it isn't the CATs nor CAT temp sensors, it has to either be the brand new O2 sensor or ....? I wonder if there is any other sensor that could be going bad...
 

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Discussion Starter · #4 ·
Replaced the same O2 sensor and still no go. I have a feeling it is the Fuel pump so I will see what the dealer says next week. I can't think of anything else it can be at this point
 

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thanks for the replies. No clue about fuel filters. Is that something easy for me to check? I am (begrudgingly) having the car towed to the lambo dealer tomorrow :confused:
Not “easy” like pulling a dipstick but not “hard” like a motor out job. All things considered it sounds best to see what the dealer comes up with. From what I know, many possible small issues can cause those codes.
 
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