hopefully some body here can set me straight, and i (we) can figure this out...

i had an SES light coming on and off. it was the P0420 code. i figured cats were starting to clog. pretty sure i was right.

installed test pipes on my car about 5 days ago. i have an 04 ( must be an 04.5 because SES light is driving me nuts) g35 coupe.

test pipes had no shielding for downstream O2's. so i put in some 18mm antifoulers, thinking that would do the trick for the SES light that i knew would be coming on soon otherwise.

no SES light for 2 days or so. driven about 50mi a day.

came on, i checked the codes and cleared them. P1167, it turned up twice. Heated Rear Oxygen Sensor 2 Maximum Voltage Monitoring Bank 2. and then showing "sending" inside the code description or something like that.

no codes for about a day and 1/2, then came back on, checked it, P1283 now. Air fuel ratio (A/F) sensor 1 (Bank 2) lean shift monitoring

im not really sure what is causing the codes at this point. i have ruled out plenum leak.

im considering:
PCV valve
ECU needs hard reset (pull 2 fuses for 10 min)
maybe injectors need cleaned?
Loose connection to downstream O2's
exhaust leak either between header/test pipe or test pipe/ypipe
antifoulers are not working.

I'm thinking its one or more of the last 3....

so if it is the antifoulers are not going to work, i was going to wire in some resistors to my downstream O2's to make them give ECU a desirable reading to clear CEL light. BUT! i am not 100% certain i know exactly how to emissions system worked on this car. i do not want to install resistors and permanently throw my A/F ratio wayyyy off.

so anyone know how the O2's read collectively? i always thought the upstreams read A/F and the down streams read for the emissions control?

if that was the case couldn't i just capp of my antifoulers over the downstream O2's and fix it? but, a friend has and A/F gauge in his 03 sedan, and he tied it into the downstream O2?

also, bank two (for the DTC codes) which sensor would that be?

 

I would re-install the bank two(driver side) pipe with new gaskets and a torque reading.

 

Do your OBD-II reader do real-time monitoring and graphing?

Might be time to plot your upstream and downstream O2 sensors on a graph and see if they are reading properly so you can tell exactly what's going on.

 

I don't have access to that type of diagnostic tool. I'll be checking for leaks tomorrow evening. I expect to find one.

 

Begin by cleaning the sensors in bank 2 (passenger side) and make sure you have no leaks in the connections. I replaced sensor #2 throwing the same code in the passenger side a week after in installed my HFCs and it never came back. My next issue shortly after was a lean condition due to all my breather mods requiring a tune to correct!
Gary

 

You might just need to get it tuned man

 

I'm tuned and my 1273 and 83 codes came back. recently fixed a manifold leak right near the PCV. fingers still crossed.