[speedyink1]

So I get, I'm within warranty, this is the dealers problem. Still, I'd like to know and this is bugging me.

August 28th I had a check engine light on: Code P2098. Fuel Trim System too Lean Bank 2.

They replaced the o2 sensor, made total sense.

Today (about a month after the first repair) the light came on again.

P2096 this time, which is for Bank 1.

So my question is, would it be logical that another O2 sensor that could be bad? I know there's more then one O2, but I still think one going would make sense, but a second one going makes me think it's something else.
Could this possibly indicate a fuel injection system issue?

Obviously not looking for a solid answer, more so, what possibilities would make sense.

Car is going in on Monday.

[Joshinator99]

Originally Posted by speedyink1

So I get, I'm within warranty, this is the dealers problem. Still, I'd like to know and this is bugging me.

August 28th I had a check engine light on: Code P2098. Fuel Trim System too Lean Bank 2.

They replaced the o2 sensor, made total sense.

Today (about a month after the first repair) the light came on again.

P2096 this time, which is for Bank 1.

So my question is, would it be logical that another O2 sensor that could be bad? I know there's more then one O2, but I still think one going would make sense, but a second one going makes me think it's something else.
Could this possibly indicate a fuel injection system issue?

Obviously not looking for a solid answer, more so, what possibilities would make sense.

Car is going in on Monday.

Intake and/or exhaust air leaks will play havoc with fuel trims.

[KingLT1]

Originally Posted by Joshinator99

Intake and/or exhaust air leaks will play havoc with fuel trims.

[GreyGhost702]

The best diagnostic way would have been to pull a data log on the car during the original incident with the first O2 sensor reporting lean. This way you could verify the fuel trims and record the rest of the system as well. Then you would have had a log to compare to this second incident. I would still pull a log before it goes in for repair, put eyes on the fuel trims.

I think if you were having an issue with the fuel system or injectors you'd have a wider spread issue than just fuel trims reporting lean. A problem with multiple injectors or even 1 injector is going to cause a constant issue and should affect performance/fuel economy. A sticky injector, leaky injector, clogged injector are all possibilities but they tend to stand out. Leaky injectors also should report rich conditions and/or knock. The fuel system, including injectors, is pretty stout on these vehicles. Given your year and expected milage, it just seems unlikely.

Since they replaced bank 2 and it no longer reports lean, I'd say it's a safe bet the O2 was out of sorts. Now the bank 1 sensor is reporting lean, if they replace that sensor and the code goes away and doesn't come back, it would be safe to say you got a crumby set of O2's. But you can fire up the scanner and take a look at the log after the sensor is replaced and compare to your log before replacement, see if there's anything out of the ordinary.

For a fuel trim to be reporting a DTC fault, it'd have to be pulling hard lean. I've watched my fuel trims dance to a rave beat during the tuning process, never experienced a DTC for it.

I tend to rule out an exhaust leak of any kind, since replacement of the bank 1 sensor corrected the first issue, and now you're experiencing the same on the opposing bank. The odds of developing 2 exhaust leaks in a month on both exhaust banks is almost as unlikely as losing a pair of O2 sensors a month apart for the same code. I don't like coincidences, either. So I encourage datalogging while they nickel & dime themselves on warranty repairs.

[speedyink1]

Thanks for the replies, gives me a better idea as to what's going on. I just mention fuel issue since I've always felt this sort of slight "mis-fire" from time to time, but after some research as long as it's not throwing a code it's probably a normal DI engine thing.

So I log it using my scan tool? It's not a fancy one by any means, but I'll see if I have the option. I like the idea of logging it myself, just to give myself a better picture of what's actually going on.

Thanks!

[ctrlz]

Is this car completely stock?

[fj5gtx]

Generally when I have a sensor issue that is one of two sensors doing the same job, I'll swap them and see if the code follows the sensor. If it does follow the sensor, I replace the sensor. If it doesn't I'm looking for something else causing the computer to throw the code.

The computer is basically following a fuel map to control injector output, based on sensor input. When sensors show deviation, it'll make alterations to that map - characterized by "Trim". You can read those trim adjustments as they are being made by hooking a reader into your obd2 port. Between looking at the sensor outputs and the computer response, I can usually discover the underlying issue.

There are cheap alternatives to what you'd see people use on youtube to read the computer parameters (like o2 sensor output, MAP, fuel trims, vac, etc). A $10 ELM bluetooth adapter from Amazon with a free android app called Torque gets you pretty far down the road. I have yet to spend any real money troubleshooting computer controlled engines.



If you have the interest, time, and thirst to learn, you can start with Matt's videos... he is pretty good at explaining how things work. He is a little full of himself sometimes, but he seems like a good dude otherwise :-)

[speedyink1]

Originally Posted by ctrlz

Is this car completely stock?

Yes

Originally Posted by fj5gtx

Generally when I have a sensor issue that is one of two sensors doing the same job, I'll swap them and see if the code follows the sensor. If it does follow the sensor, I replace the sensor. If it doesn't I'm looking for something else causing the computer to throw the code.

The computer is basically following a fuel map to control injector output, based on sensor input. When sensors show deviation, it'll make alterations to that map - characterized by "Trim". You can read those trim adjustments as they are being made by hooking a reader into your obd2 port. Between looking at the sensor outputs and the computer response, I can usually discover the underlying issue.

There are cheap alternatives to what you'd see people use on youtube to read the computer parameters (like o2 sensor output, MAP, fuel trims, vac, etc). A $10 ELM bluetooth adapter from Amazon with a free android app called Torque gets you pretty far down the road. I have yet to spend any real money troubleshooting computer controlled engines.



If you have the interest, time, and thirst to learn, you can start with Matt's videos... he is pretty good at explaining how things work. He is a little full of himself sometimes, but he seems like a good dude otherwise :-)

Cool, that's interesting stuff! I'm going to try to learn some of this for sure. I like to know how things work, I don't like not knowing how parts of the car work. I get how a lot of the mechanical stuff works, and therefor I can take care of them properly, but the computer part of it is a bit beyond me

[Megahurtz]

Excessive misfires can cause a lean code as well.