05PRMTX

Started up my Car Saturday night and the idle was extremely rough. Shut it off, turned it back on and it was fine but the check engine light came on. Plugged in the tuner and it had the P2196, and P2198 O2 sensor biased/stuck rich codes. Motor is stock, no tune. Can it be as simple as bad sensors? Going to take it in as its due for some regular maintenance anyways, and I don't have a garage to mess with it in at the moment...but I jut wanted to get some insight if I could before hand. (bank 1 sensor 1, bank 2 sensor 1)

houtex

Both sides reporting rich? Well, that *could* be sensors... could be a shorted wire... could be an injector each side is leaking... It's very odd that both are hitting that code, given they're on either side of the engine. Both sides is kinda a low odds thing, ya ask me...

So, small investigation time! If I look at this wiring diagram...
http://iihs.net/fsm/?d=711&f=024%20-...205.0L.pdf&p=8

And I see HEGOs #11, 12, 21 and 22, I can hopefully assume that Bank 1 Sensor 1 is #11, and Bank 2 Sensor 1 is #21? But that's not terribly important. Look at the VT-GY line that all of them get power from. That goes to here:
http://iihs.net/fsm/?d=711&f=024%20-...205.0L.pdf&p=7

On the upper right. The power comes from the Battery Junction Box (fuse box under hood) and then splits off to the Evap purge valve, the four camshaft timing solenoids, the four HEGOS (F, G, H and J) and the skip shift solenoid (N), shown here:
http://iihs.net/fsm/?d=711&f=024%20-...205.0L.pdf&p=9

And now with that covered, here's the culprits possible in no particular order:

1. Both 'front' HEGO sensors are bad. Replacing them may solve the issue. Not all that likely, IMO.
2. Both banks have at least one leaky fuel injector causing a rich condition in a cylinder each side. Not all that bad a guess, dirty injectors could stick a little open...
3. Wiring issue. Could be a loose/frayed/shorted cable to the HEGOs or the power going to them, wherever it's coming from, is compromised up the stream... That's a fun project to figure out. I also vote not as likely because one but not both, they don't otherwise share wiring except the power hot in key on/run.
4. Bad connectors. Either the HEGO connectors or somewhere else in the harness, all the way back to the computer or the battery junction box (fuse box under hood). Which is sorta 3 related, but not exactly the same.
5. Bad powertrain computer. Which would be surprising, but not out of the question completely.

So there ya go. Can't advise further, you're better off getting it diagnosed properly and doing it right once, not shotgunning it with a parts chase. Meaning I'd hold off on the HEGOs until it was determined absolutely to be needed. I mean, they're something like $100 each side, be a shame to spend the bucks and it not fix...

05PRMTX

Wow, Great info! Thank you! So a little update. I disconnected the battery to let everything reset and see if i get the same codes again. I haven't done a lot of driving since, but the codes have not come back. I have had a few rough grumbles on startup, but that's about it. Have also noticed some hesitation/bogging around 4k rpm, which may support the injector ( #2) issues. I don't want to send a mechanic on an expensive, wild goose chase, but may have to take it in at some point.

houtex

Hm. Makes me wonder if your battery is good, and/or your terminals are good, and your grounds are good. Maybe check those.

Here's a lil' thing to read regarding such. Relates to the battery drain issue, but may still be applicable.
https://themustangsource.com/forums/...4/#post6917899

05PRMTX

I had the battery replaced a few months ago. I've had enough weird battery issues with cars to not rule that out though