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Bought a 2006 350Z Touring for my son with 111k on it. Aftermarket items are Kinetix intake, NWP throttle body and invidia exhausts. Not sure what the make is on the test pipes.

day after purchase P2A00 and P2A03 codes came on and stayed on( if I delete code with the OBD2 it comes back in about 20 miles)

after reading a few forum discussions looks like the common items are:

O2 sensors- but would both fail at the same time?
Exhaust leaks before the TP’s
MAP leaks
Faulty fuel injection system
Faulty engine ground wire
Vacuum leak.....

one discussion claimed that issues with the downstream sensors might cause the two upstream ones to throw the fault? Any info on that....

currently getting P2A00 and P2A03- so both A/F 1 sensors in the exhaust manifold. Any suggestions where else to look? Car has to be able to pass emissions in TN

thanks
 

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Welcome- any of the mods you mention could be the source of one or both of the codes. Also, using test pipes and deleting the catalytic converters will usually trigger a CEL. If you need to pass emissions, that may be a game stopper. Did you get any of the OEM parts with this sale? Did you have the car inspected before purchase?
 

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Car was bought as is- no oem parts.... wouldn’t surprise me if the dealer cleared the code before the sale as it came on after an hour or so....

long story- but hard lesson to learn. I have never thought about having to check if the car has cats....and I’ve bought a few in the last 30 years....

car somehow passed emissions ( had to for registration- light was out at the time.... so I have a year to figure it out.) Some suggest a tune- Uprev, etc for $500-$750.... , aftermarket HFC’s ...others suggest looking at the common items in my last post. I just don’t want to throw good money away. Car seems to run fine-
53308
the only suspect issue I saw after a quick look was twisted wire in one of the downstream sensors- but that is not supposed to throw codes upstream? One post I read suggested that it could, but no one else seems to agree or acknowledge it.

Guess I’ll start with the leak detection / grounding issue first and live with the light for a while
 

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I think that's a good strategy- start with looking for leaks around the MAF and TP. This can be an issue with aftermarket CAIs. Then check for ground issues (which is always something good to check with an unknown used car). BTW- there's no way any of us can really diagnose issues like this from behind a keyboard. You're in the best position with being hands-on. But it may be helpful to know that those codes are not common or endemic with the 350Z at any mileage level.
 

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Something that I read on every automotive forum - especially here and the other 350Z forum - is people wondering why they get upstream (or downstream FTM) errors with test pipes (IMO, the silliest "improvement" that does nothing but create issues while delivering, well, not much of an exhaust improvement).

Well, if you consider that the reason for an upstream and downstream sensor is to measure the before and after (catalyst) oxygen content and then you take the cat out of the equation leaving an upstream and downstream without any delta (exhaust content is not altered in the 12-14" of straight through pipe), the ECU interprets this as a fault in the 02 sensor circuit. The only way to "trick" the ECU is to enshroud the downstream sensor with a shield that limits the amount of oxygen/exhaust content it can read so there is a delta between up and downstream sensors. The problem with these shields is that there is no science behind them - as in a design to limit a precise amount of exhaust to create the perfect before-after delta between up and down sensors. Consequently, the delta is still not correct and the ECU attempts to adjust the fuel/air mix and timing based upon the info it's getting. So, GIGO applies here, garbage-in-garbage-out because the ECU is properly interpreting improper data; resulting in a loss of power AND/OR poor mileage from too much fuel being delivered according to the reading.

Can you tell I have a high intolerance for "test pipes"? I did this back in the 70's and found out just how intolerant fuel injected engines are when you mess with the sensor readings by tossing out the catalyst in search of power and/or "cool sounds". Ehhhh, lame.
 
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