Please help! - Lean code P2098
 

Hello, hoping someone here can shed some light on my issue before I start replacing unnecessary parts.

- Recently had a P2098 (post catalyst too lean bank 2) code appear, this was the day after fueling up (yes, premium octane with receipt to prove it). Took car to the dealer, they suspected bad fuel and did a flush. Same code came back the day after. Mind you, the code doesn't appear until about 30 minutes of driving. Took it back to the dealer, and they wanted to replace my bank 2 upstream sensor. Of course they wanted my firstborn, so I bought a new OEM sensor and planned to do it myself. Next day code P2097 appeared (post catalyst too rich bank 1).

- Replaced the upstream bank 2 sensor, still have the issue.

- Replaced all spark plugs with new OEM, still have the issue.

- Exhaust stinks, suspecting a rich condition.... ?

- Catalyc converters are quiet, don't rattle when operating or when tappin on them.

- All exhaust connections are tight, gaskets intact and accounted for.

- Intakes are connected properly and undamaged, filters clean.

- No vacuum leaks detected.

- Dealer stated they did a full fuel system clean; tank, filters, injectors etc.

- Car runs pretty terribly, loss of power, not smooth etc.

Should I be replacing injectors next? Or??? :facepalm:

Id would expect a bad injector to also throw a code. A did quick google on misfires; typically its p0300. No way the dealer should have overlook that, but I would get an odb reader and re check

Has the car been tuned? ECUTEK or UpRev? Miles on the car?

Upstream sensors control your air/fuel ratio. It is entirely possible that the throttle bodies need cleaning.

I have an OBD reader, only codes are the P2098 (bank 2 lean), and P2097 (bank 1 rich) which is sporatic and does not come back each time I clear the codes.

Have never had the P0300 code.

Car has not been tuned, about 35k on the vehicle.

According to the dealer, they cleaned the throttle bodies. When I had them off to change the plugs, they looked relatively clean. I re-installed the intakes and bodies, they are secure and tight.

I have also recently had the exhaust system (after the cats) off several times, during the clutch/flywheel install. But everything is tight and there are no leaks that I can detect in the exhaust connections.

How does the car run at idle and full throttle?

If you haven't already, I would clean the MAFs. I understand the milage is very low, but dirty MAFs don't accurately report the air flow and then we can rule that out.

As for replacing your fuel injectors, I wouldn't do that just yet. Let's dig into this a little bit more. It can get very expensive throwing parts at a problem.

Let's look at what data is being reported to the ECU.

If your OBD scanner can show live data, with the car warmed up and at idle make a note of:
• Short term fuel trim bank 1
• Long term fuel trim bank 1
• Short term fuel trim bank 2
• Long term fuel trim bank 2

To find the total fuel trim for each bank, add the short term and the long term. They should be between -15 to + 15.

Also:
• Mass air flow sensor A
• Mass air flow sensor B

At a hot idle of 650 RPM, the air flow for both banks should be very close to 2 g/s
(If your elevation is high, the value will be lower)

and finally:
• O2 sensor lambda (Bank 1, Sensor 1)
• O2 sensor lambda (Bank 2, Sensor 1)

At idle they should both be 1.0 (or air/fuel ratio of about 14.7:1)

If your OBD scanner doesn't support live data, you might want to purchase a quality bluetooth LE OBD scanner for around $30 (Veepeak BLE, iCar Pro, etc) Avoid the $10 scanners, most of them are very slow and I have received a few that were dead and then needed to go through the process to get them replaced.


A good OBD app is OBD Fusion (< $15) and has a very comprehensive diagnostic report, that reports the values of all PIDs, misfire counters, and other good stuff. For under $50 you have a good diagnostic system with data logging capabilities that you can use on any car made after 1995.


Anyways, I hope that you can provide the live data, and we can continue to hunt this down :)

Thank you so much for this!! Going to look when I get home from work. I do have an lcd OBD sensor, and it does show live data, but wasn't sure how to interpret it. I have also ordered a touchscreen "LAUNCH OBD2 Scanner CRP123E" that should be here nextvweek. Will try what you said and reply back!!

Car seems rough at idle and acceleration, loss of power. Nothing like it used to be.

Also, I did clean the MAFs with MAF cleaner. They looked pristine, but I cleaned them anyway.

Ok, did what you said, my OBD scanner is rather rudimentary so I will give what I have and hope it makes sense....

These are the average trim readings during idling warmed up:

SHRTFT1(%) = 0.8 <----:confused:
LONGFT1(%) = -7.8
SHRTFT2(%) = 8.6
LONGFT2(%) = -7.8

Not sure which reading relates to MAF sensor A + B, but here are the other average stats...

O2B1S2(V) = 0.7
O2B2S2(V) = 0.05

Cat temps on both = 147.20

EQ_RATB1S1 = 0.996
O2B1S1(V) = 2.29
EQ_RATB2S1 = 0.975
O2B2S1(V) = 1.905

Here is what I see:

• The fuel trims are within the normal range - good!

• O2B2S2(V) / O2B2S2(V) -> this is the rear o2 sensor voltage. A single "snap shot" of this data doesn't tell us anything. A datalog of about 1-2 minutes does tell us a lot, but I suspect your OBD tool doesn't have that function.

• Cat temps: This is a calculated value based on engine demand. It doesn't really tell us anything for this issue.

• EQ_RATB1S1 = 0.996 / EQ_RATB2S1 = 0.975: This is the equivalence ratio (aka lambda). Multiply it by 14.7 to get the air/fuel ratio. (bank 1 is ok, bank 2 is a little rich)


• O2[b]B1[\b]S1(V) = 2.29 / O2[b]B2[\b]S1(V) = 1.905 / This is the output voltage from the air fuel sensors. At idle / low engine load (air/fuel ratio of 14.7) they should be 2.2 volts. Bank 1 is a little lean bank 2 is a little rich.

As you can see, the data contradicts the trouble code.

Keep in mind the data above is a "snap shot" in time. Often the engine computer will adjust up and down and then perform an analysis to determine a average. If the average is out of a predefined range, a trouble code will be set.

A common cause for one bank to be rich and one bank to be lean incorrect crankshaft/camshaft timing. Luckily, this doesn't normally apply to out engines.

I think it is best to take it to a shop. To continue to trouble shoot requires special tools and knowledge, as I see it.

Maybe someone else will see something I missed. - Good luck!

I have replaced the clutch and flywheel, is there something I could have done wrong that threw off the timing?

I would watch b2s2 and bank1s2 on your scantool (that’s the actual o2 sensor) from your post it looks like you’ve replaced the a/f sensor (b2s1). If you can graph both rear sensors and hold rpm steady at 2500, or have someone drive with you watching the line graph there should be even waveforms at steady rpm. If bank 2 o2 is switching to fast or slow compared to bank 1 I would suspect a bad o2 sensor causing the P2098 code. Very common for that to happen.

Ok, I will work on that and reply back. Which o2 sensor is that? Downstream or maf sensor? Bank 2?