2006 M35-Service Engine Soon Light-Oxygen sensor aren't reading

[Korben15]

Ok guys, my computer is messed up. I got the SES light and it said the bank 2, sensor 1 was bad so I replaced it. Then it said sensor 2 was bad but after I cleared that code, it said sensor 1 was bad again. I'm pretty sure my ECM(?) is bad and needs to be replaced. Has anyone done this? Can I buy a used ECM and then have the dealership program it for my car? If anyone has some experience with this, please chime in.

[EdBwoy]

Yes, you can buy an ECU and have it programmed, but I bet you could save some money or DIY time buy following the O2 sensor a little further. I havent had to have a ECM programmed, so I'm not sure of the cost or how different the ECMs would be depending on vehicle packages, but I don't think the computer is bad.
Did you replace the bank 1 sensor with a brand new OEM sensor?
Could you try swapping the bank 1 and bank 2 sensor 1 to see if the code follows the sensor?

[Korben15]

I've already replaced the sensor for Bank 1 and 2 and the code is still showing.

[EdBwoy]

I was asking if you have swapped them to see if you by chance have a defective sensor. It happens

[Ilya]

What is your actual P code? It's possible you replaced O2 sensors when your issue was with the catalytic converter, etc.

[Korben15]

P2A03-I've had it into the dealership & even they said the o2 needed to be replaced. The reason I think it is the computer is because the code 'jumped' from one sensor to the other, after having replaced the first, then it jumped back to the first again.

[Ilya]

Hmm, interesting indeed. That is the code for an O2 sensor...did you release the pre-cat O2 sensors or the ones at the bottom? Both sets have a bank 1 and a bank 2...or did the dealer do the work? If the dealer did the work I would imagine they changed the right ones...but you never know.

[cruzad3r]

it's not your ecu, you need to check the cat and potentially replace it. ebay has the direct fit for abt 155 shipped. i just bought the passenger's side to replace and get rid off the p2a00 code.

also check for vacuum and exhaust leak too.

[Korben15]

Thanks for the suggestion cruzad3r. Is it bad if I drive around with this code? I've replaced sensor 1 for bank 1 and bank 2, so I'm pretty sure it's not actually a problem with the oxygen sensors.

[EdBwoy]

This is one of those that I'd have loved to throw more time at to diagnose, or asked the dealer to do what it takes to make the code disappear if I didn't have time.

But no, there really shouldn't be any catastrophic issues with driving with a bad sensor. The immediate effect would be loss in performance/drop in mpg.
At worst, and this is a slim chance, the catalytic converter might get damaged.

The code says that the sensor is either bad or you have a fuel or intake issue. I am going for something common since it has affected both banks.
Are you clearing the codes as you go or just letting the car figure out and throw a new code?
I'd check your intake tube around the MAF sensor. It's possible for the rubber to have a rip or the clamp to come loose.

Could you tell us who did the work and what the source of the replacement sensors was?

[Korben15]

How easy is it to check the catalytic converters? Is it worth it to have it diagnosed at the dealership for $100 or can/will SN exhaust shop check it quickly for free?

[Korben15]

This is one of those that I'd have loved to throw more time at to diagnose, or asked the dealer to do what it takes to make the code disappear if I didn't have time.

But no, there really shouldn't be any catastrophic issues with driving with a bad sensor. The immediate effect would be loss in performance/drop in mpg.
At worst, and this is a slim chance, the catalytic converter might get damaged.

The code says that the sensor is either bad or you have a fuel or intake issue. I am going for something common since it has affected both banks.
Are you clearing the codes as you go or just letting the car figure out and throw a new code?
I'd check your intake tube around the MAF sensor. It's possible for the rubber to have a rip or the clamp to come loose.

Could you tell us who did the work and what the source of the replacement sensors was?

I bought the sensors from an Infiniti dealership. I had a local shop nearby replace the sensors, they've done work on several of my family members cars, Kane's Automotive in lewisville, Tx.

[cruzad3r]

the only way to correctly check the cat is to take it out and shake it. if the internal core is moving, then it's shot. i bought a set from a user off g35driver and the passenger side was bad. that is why i had to buy a direct fit aftermarket one to replace it. i'll post pic when i have time.

i was driving my car with the P2A00 code for a good 3-400 miles without noticing anything different (performance wise) but the check engine light on the dash does bother me. again, if you swap out both bank 1 sensors and still having the code, the next step is the cat converter. if that checks out, then leaks. Oh another tip is to check your long term fuel trim and short term fuel trim. rich/lean conditions will throw the code "so i'm told by others who had this issue"

[Korben15]

The dealership told me that they catalytic converters are working fine and aren't blocking exhaust from passing through, but then they said the catalytic converters could be 'bad' and could cause the code to be thrown..........? Catalytic converters don't just go bad, right? They either have broken apart or they haven't. I have aftermarket ones on there that weren't expensive, but as they said, they're not blocking exhaust gas from escaping. I paid for Infiniti to check it out and they that the computer can't read the code right from sensor 2. Like I said, I just replaced sensor 1, cleared the code, then the code for sensor 2 showed up. I cleared that, then they code for sensor 1 showed up and the dealership said they found the code for sensor 2. Any one got an idea on what I should look at for my described problem?

[bakili]

The dealership told me that they catalytic converters are working fine and aren't blocking exhaust from passing through, but then they said the catalytic converters could be 'bad' and could cause the code to be thrown..........? Catalytic converters don't just go bad, right? They either have broken apart or they haven't. I have aftermarket ones on there that weren't expensive, but as they said, they're not blocking exhaust gas from escaping. I paid for Infiniti to check it out and they that the computer can't read the code right from sensor 2. Like I said, I just replaced sensor 1, cleared the code, then the code for sensor 2 showed up. I cleared that, then they code for sensor 1 showed up and the dealership said they found the code for sensor 2. Any one got an idea on what I should look at for my described problem?

Did you figure it out? I just changed both A/F upstream sensors and put new Kinetix cats. I can see that I'm already getting a better gas milage. P2A00 showed up after 70 miles though. I double checked that I attached my new cats well, shook the whole exhaust and when the car was on watched to see if I could see any exhaust leaks but couldn't, but I'll check again though. Also, I know my air intake rubber seal between air filter and the Z tube is torn and patched with tape. Before I didn't get P2A00, maybe it was because A/F sensors were not working well to detect an air leak?

[bakili]

OK, I double checked and saw that one of the bolts on passenger side pre cat (Bank 1 Sensor 1) loosened. So in my case the culprit was exhaust leak, air intake prior Z-tube even though is not perfectly air tight is not pressurized, as such I did not consider it as number one suspect. I guess new sensors work really well! And just passed inspection

[Ilya]

The dealership told me that they catalytic converters are working fine and aren't blocking exhaust from passing through, but then they said the catalytic converters could be 'bad' and could cause the code to be thrown..........? Catalytic converters don't just go bad, right? They either have broken apart or they haven't. I have aftermarket ones on there that weren't expensive, but as they said, they're not blocking exhaust gas from escaping. I paid for Infiniti to check it out and they that the computer can't read the code right from sensor 2. Like I said, I just replaced sensor 1, cleared the code, then the code for sensor 2 showed up. I cleared that, then they code for sensor 1 showed up and the dealership said they found the code for sensor 2. Any one got an idea on what I should look at for my described problem?

Cats will loosen over time and work less efficiently...this is where the sensors read the 'value' of the exhaust and determine if it's still optimal (good) or less than optimal (not so good) or flat out wrong (bad).

I quickly scrolled through the thread and didn't see mileage listed but if you are at any sort of high mileage the cats could certainly be out and it's time for a change. Or you have an exhaust leak like has been stated which is throwing off the reading (making it lower than expected).

OK, I double checked and saw that one of the bolts on passenger side pre cat (Bank 1 Sensor 1) loosened. So in my case the culprit was exhaust leak, air intake prior Z-tube even though is not perfectly air tight is not pressurized, as such I did not consider it as number one suspect. I guess new sensors work really well! And just passed inspection