MatthewJ

Have had a CEL for about 2 weeks now. Car idles and drives same as always, has full power too. Gas mileage to and from work is unchanged.
Yet i keep getting these two active and pending codes even after clearing them:
P2196 ( primary bank 1 O2 rich condition) and P2097 (secondary bank 1 O2 rich condition)
I know the obvious thought is i have a rich fuel condition on bank 1 (passenger side), but i cant find anything else that would suggest that.
Air filter are only about 6 months old and look mostly clean still,. Logs show good and consistent boost numbers on both banks.
Fuel pressure is within normal range at different loads and WOT. I dont have a scanner that can check/graph the O2 volts to see if the primary one is bad, but that is the only thing i can think of, is that sensor is showing shifted data. But if thats the case and its telling the ECU the bank is rich it would pull fuel and i shouldnt get a rich condition from the "post cat" sensor.
I have tried reverting to older JB4 firmware but it doesnt seem to effect anything.
C400 w/40k miles- catless downpipes with secondary O2 spacers and JB4 map 6

Anyone have thoughts on this before i start swapping primary O2 sensors?

TModelle

Try running a few days with the JB4 completely removed.

MatthewJ

I removed the JB4 and will test a few days without it.
next step will be pull bank 1 plugs and see if there is anything alarming like fuel on them. Then I'll try swapping O2 sensor between banks.

jatt143

I had issues with my JB4 and similar codes coming up. burger tuning replaced my jb4 tuner and it worked fine for another month. I was back to the same codes and symptoms with the car. removed jb4 and completely and took the car to the dealer they reflashed ECU to the factory and since then it's been running good.

I suggest removing jb4, if code is still there get the ECU flashed to factory

MatthewJ

Removed JB4 completely and drove about 20 miles before the CEL came back on with the same codes.
Going to just order a new primary O2 sensor. maybe mine just got fouled up or something.

MatthewJ

Update:
New primary oxygen sensor installed(MB part). Rich condition on the scanner had gone away. Both banks show same A/F ratio now and fuel trims are looking good. Seems to have fixed my issue.

MatthewJ

Might have spoke too soon. Fuel trims looked much better on the scans but yesterday afternoon the CEL came back with the same 2 codes for bank 1 rich condition.
Plugs all look good and i can smell no fuel in the cylinders with the key on and plugs out.
Out of options now. maybe unplug the battery? is there a way to reset the ECU?

TModelle

Faulty EVAP valve.

MatthewJ

does it vent back to only bank 1? and wouldn't that throw a separate code? most emission controls have several separate codes.

TModelle

Sorry, I thought you said both banks. My bad.

MatthewJ

No worries. I appreciate the response.

Anyone know which cylinder is which on the M276? I am assuming the #1 is passenger side front most cylinder but maybe not?

EDIT: Turns out the O2 spacer i had on the SECONDARY sensor was loos on one of the joints and letting air past it. I wasnt aware our cat/emission sensors can control fuel trims to an extent (-+5 ?) causing the car to add fuel on that bank when it didnt need it and gave me the rich condition.
Hope this saves someone some confusion, check the spacer parts for looseness on the secondary oxygen sensor...