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Engine light (P2098) after fill up

28K views 12 replies 7 participants last post by  irunnoft 
#1 ·
WHAT'S YOUR THOUGHTS?
Ran the tank down to near empty. Decided to go to a different gas station on my way to work to fill up [87 octane since I've owned the car]. About 35 to 40 miles later my engine light comes on [38,200 mile].

Coming home from work, stopped at the local auto parts store to get the code - yep! [2098]. By the way it is the only code. On the way home, I put some gas treatment in the tank. Thought it might be water. Since then, have ran the tank down to about a 1/4 and filled back up again with 92 octane. Engine light still on.
Should I continue with another tank or two at 92 octane and more gas treatment?
Do these lights go out on there own, assuming its a gas contamination issue?
Have not checked for an exhaust leak yet.
Have not pulled the old battery cable trick (assuming it would come back on anyway).
Do I need to get it flashed? (there goes $150)
Currently the car runs awesomel.

Do I keep doing what I'm doing or take it in for reflash and get the exhaust checked?

Sorry for the same old but after 6 different vehicles across 3 different manufacturers, these O2 sensors are quite irritating. What a racket!

'09 R/T

Thanks for your feedback
 
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#2 ·
I believe 2098 refers to a lean mixture on the left bank. I wouldn't think the octane rating has effect on that. Have you done anything to the engine to get more air in with out tuning (adding more fuel)?

Exhaust leak?
 
#5 ·
I believe 2098 refers to a lean mixture on the left bank. I wouldn't think the octane rating has effect on that. Have you done anything to the engine to get more air in with out tuning (adding more fuel)?

Exhaust leak?

Bank 2 is the passenger side.
 
#4 · (Edited)
All of the below said and done, I'd reset your long term fuel adaptives by pulling fuse #2 for 10 seconds, drive 3 trips, and see if the code goes away.

If anything, since you got so low on fuel, you might have had some sediment go through your fuel system. That and the station you filled up at from after work had crappy gas.

One bottle of fuel treatment, don't waste your money on more as you'll need 3 good trips to reset the code... or clear the code with the predator... or go to the dealership to clear the code.

P2098-DOWNSTREAM FUEL TRIM SYSTEM 2 LEAN

When Monitored:
With the engine running in closed loop mode, the ambient/battery temperature above (-7°C) 20°F, altitude
below 8500 ft and fuel level greater than 15%.

Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a certain percentage is exceeded for
two trips, a freeze frame is stored, the MIL illuminates and a trouble code is stored. Two Trip Fault. Three good trips to turn off the MIL.

Possible Causes
EXHAUST LEAK
ENGINE MECHANICAL PROBLEM
2/2 O2 SENSOR
(K243) O2 2/2 SIGNAL CIRCUIT
(K399) O2 HEATER 2/2 CONTROL CIRCUIT
(K904) O2 DOWNSTREAM RETURN CIRCUIT
FUEL CONTAMINATION

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test

1. ACTIVE DTC
NOTE: Check the vehicle repair history. If the 2/2 O2 has been
replace make sure that the O2 sensor was properly installed and
meets OEM specification.
NOTE: Check for contaminants that may have damaged the O2
Sensor: contaminated fuel, unapproved silicone, oil and coolant.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform (NGC) POWERTRAIN VERIFICATION TEST VER
- 5. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/POWERTRAIN CONTROL MODULE - DIAGNOSIS
AND TESTING)
P2098-DOWNSTREAM FUEL TRIM SYSTEM 2 LEAN (CONTINUED)

2. EXHAUST LEAK
Turn the ignition off.
WARNING: To avoid personal injury from the exhaust system being hot, allow the exhaust to cool down to
a safe temperature before performing a physical inspection. Failure to follow these instructions can result in
personal injury or death.
Visually and Physically inspect for holes, cracks and blockage in the exhaust system.
Is the exhaust system is good condition?
Yes >> Go To 3
No >> Repair or Replace as necessary.
Perform (NGC) POWERTRAIN VERIFICATION TEST VER - 5. (Refer to 8 - ELECTRICAL/ELECTRONIC
CONTROL MODULES/POWERTRAIN CONTROL MODULE - DIAGNOSIS AND TESTING)

3. ENGINE MECHANICAL PROBLEM
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from leaks
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector
Are there any engine mechanical problems?
Yes >> Repair as necessary.
Perform (NGC) POWERTRAIN VERIFICATION TEST VER - 5. (Refer to 8 - ELECTRICAL/ELECTRONIC
CONTROL MODULES/POWERTRAIN CONTROL MODULE - DIAGNOSIS AND TESTING)
No >> Go To 4
 
#6 ·
When you refer to a possible leak in the exhaust, are we looking from the manifold to the cats only? (Sorry for my ignorance here)

A little more history; I have replaced the suitcase muffler in the middle with Flowmasters 44's and removed the two carry-ons in back and replaced them with straight pipe. All at around 19,000 miles (currently at 38,200). Great sound by the way!
Is this allowing the exhaust system to breathe to easy?

I'll try the F2 fuse and check the gas cap.

Thanks for your help.
 
#8 ·
Hey I had a similar experience. When I bought my car, the salesman filled it up with 87 octane gas. I never had any issues with sputtering or stalling. The car seemed to work perfectly.
I ran a 1/4 tank down from that full tank of 87 and then topped it off with 93 octane.
I did the same thing one more time and then I drove it until the car had about 1/4 tank of gas left.
Then I filled it up with 93 octane (that was last night). Since the fill up last night, I've driven about 40 miles or so and then the MIL light came on this morning. It isn't flashing. I checked the gas cap and it was fine. I stopped for lunch not long after the light came on and when I went to drive back home, it still stayed on.

What's the prognosis? Is it crappy gas that the dealership used? They filled it up at a BP Station. And I filled up at a Shell station last night. In fact, Shell is the only gas I've pumped in the car since I got it.

Could it be contaminants from the 87 that got mostly run down? I would think the 93 would be the optimal gas to put into this car.

Any thoughts/help would be appreciated.
 
#12 ·
Several parts houses, Auto Zone, O'Riley ect will pull the code and can clear it for free if you want to avoid the dealer. They should have known to fill it with premium. The light usually needs to be cleared, I don't know of any condition that corrects itself and turns the light off.
 
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