Fault Codes P2197 AND P2198 together
 

2197 is O2 Sensor Signal Stuck Lean bank2 Sensor1, 2198 is O2 Sensor Stuck Rich bank2 sensor1....both occur when code is thrown. Does this narrow down what could be the issue?? I have read, as usual, it could be any number of things, but seems to occur after truck is warmed up. Some vacuum leak or simply a bad O2 sensor??

Looks to me like you have a leaking fuel injector on one of the bank 2 cylinders.

I'll look at that. Thank you. 117k miles.....SO many things it could be. BARO at roughly 30 mm Hg...I AM at sea level. MAF Sensor probably OK. STFT B1&2 4.69%...LTFT B1&2 5.47%....Sensors for each bank balanced equally (3.91% S1, 99.22% S2, each bank), as well, and voltage testing OK. Seems all O2 sensors are functioning. I replaced the fuel filter, since I have not since 50k miles. No change. Will try PCV tubes next. Also a vapor fuel line coming out of a box on the firewall seems dry rotted. Maybe sucking air. This is not my profession, and I am perhaps spending more than I would if I went to my Ford guy, but I AM willing to learn. Seems that something is causing downstream sensor to detect "lean" condition. Probably some un-metered air getting in. Am I wrong??

Harness good. Not getting P2198 any longer. Not sure why I got it in the first place, but I have changed fuel filter, wrapped the PCV/vacuum hose/tubing in rubber tape, and reseated the hose clamp going from the baffle into the plenum (it was boogered up). MAF sensor is clean and intake box is sealed. Cleared code and drove truck in both highway and surface road conditions. Code reappeared on surface road with different numbers. Not sure what they mean, but they are NOT balanced any longer....STFT B1: -2.34, LTFT B1: 4.69, STFT B2: 53.13, LTFT B2: 3.13, Eng RPM 1100.00, Veh Speed 31.69 mph.

B2S1 reading is what is throwing the code. Next thing to try?

Next day Freeze Frame:
STFT B1: -1.56, LTFT B1: 5.47, STFT B2: 53.13, LTFT B2: 0.00, RPM 1832, Speed 65.9 mph. Obvious B2 issue. No misfires...Perhaps a slightly clogged injector, but not enough to throw a misfire DTC?

I will put injector cleaner through the system.

Most of the time fuel trim readings like yours indicate a vacuum leak.
At idle long term would be high and not necessarily balanced. Short term would be minus.
At 2,000 rpm long term should eventually even out and so would short term.

You have looked for a vacuum leak and didn't find one - yet. Maybe the intake manifold gasket is leaking?
A smoke test may eliminate a vacuum leak as a cause.
In any case I think the fuel trims are the best clue to what's wrong. There some good fuel trim video explanations on YouTube.
(Not a professional, just a duyi guy),
Richard

gwcloud,

My neighbor suggested a smoke test. Looks like that's next. Thanks for the info! BTW...if my scanner (Innova 3160g) is saying all 4 O2 sensors check "OK" then they are OK, right??

I think your scanner is right on the 02 sensors. Let us know if a smoke test is definitive.
Good luck,
Richard

Passed smoke test. I may be confused, too. I'm getting P2197 and most of the Youtube vids on "Ford Lean Code" related searches mention P017X codes...usually P0171 and 74 related to intake leaks. As a further issue, I got another pending P2198 (B2S1 rich) code this morning after driving about 10 highway miles, then returning to idle at an exit stoplight. Started idling rough, got code, then it smoothed out after a moment while sitting there, and the fuel trims on both banks returned to normal. I happened to be watching real time data on the fuel trim and watched the STFT reduce to -29% which explains the code, just not why. Before I got another 4 miles at about 60mph, the P2197 reoccurred. B2S2 registers 0.00 while the STFT is that high (53%) or low (-29%). Still no misfire codes, but could it be a fuel injector like alloro suggested? If so, not sure how to isolate which one with no cylinder misfiring. Fuel Pressure on that rail is 67 lbs.

I am confused too. - After you get the problem fixed the confusion will go away. ha ha I an just a diy guy too.
Looks like a condition that cycles. Of course if it were steady it would be easier to solve.
Here is a good fuel trim video I have read here on the forum that there is a big rubber elbow on the back of the intake manifold that goes bad.

The recurring B2 STFT -29% is because that B2 S1 is reading too much fuel in the exhaust gas and it is telling the B2 injectors to shorten the pulse rate - back off.
B2 STFT +53% is because the B2 S1 is reading a lean mixture and is telling the injectors to lengthen the pulse rate - feed me more gas.
The S2 sensors read exhaust gas after the converter and are monitoring the exhaust gas but do not command the injectors to react.
The pulse rate on injectors should be equal on a bank normally.
I have read more than one article that Ford systems are reluctant to report cylinder misfires. That makes it difficult to pinpoint a miss until it gets pretty bad.
Wish I knew more, good luck,
Richard 2007 Navigator

Thanks, Richard. That guy (above) is the only reason I understand FT at all. I really liked both of his FT vids, and understand the theoretical implications. I also found some vids that showed overlapping graphs in real time so you could see the relationships visually. It's pretty interesting to me. I smoked and pressurized the intake side enough to blow out 3 - gallon Ziploc freezer bags into the filter box (LOL) and got no leaking smoke out of anything on the top end. Ford guy mentioned that elbow on the back of the manifold. I am going to another buddy who has a high end scanner to do a test measuring the power balance between cylinders. Says it may very well be a sticking injector, and the test should ID which cylinder (if that is what it is). I appreciate your time and your thoughts. Thanks again.

pdqford,
Right you are. I didn't need to be that simple. Oxygen sensors measure oxygen.

jhedrick
Glad others are helping too.
Richard

Jim,

I did check back there. Injector test this morning shows nothing out of the ordinary. While driving back watching live data again, Bank 2 STFT went rich quite a few times, with very rough running while at highway speed. But code still shows lean condition.