A proper air-to-fuel ratio is essential to an engine’s efficiency. When a car doesn’t have a correct air-to-fuel balance, it can result in multiple issues. When you are looking at a P2098 trouble code, this is the case.
Keep reading to learn what P2098 means, its common causes, how to fix it in the proper way, and if you can continue driving your car until the problem is resolved.
What Does Code P2098 Mean?
The OBD-II Trouble Code P2098 means “Post Catalyst Fuel Trim System Too Lean (Bank 2)“.
All vehicles are fitted with oxygen sensors in their exhaust system these days. There are “upstream” of the exhaust manifolds and catalysts on the vehicle, and “downstream”, which is behind the catalytic converter.
Both upstream and downstream sensors are critical in providing accurate/potentially inaccurate information on air-to-fuel ratios and catalyst efficiency.
Regarding DTC P2098, data relayed from a vehicle’s downstream post-catalyst oxygen sensor(s) suggests a lean condition exists, which means the exhaust system is taking in an excess of oxygen.
This information has been logged as occurring in Bank 2 of the engine.
Generally, the management software for the affected engine will attempt to compensate for the perceived “lean” condition by adding more fuel to the affected bank.
While this is a correct action in the case of a true lean condition, however, if the lean conditions were the result of faulty or unreliable feedback, a “rich” condition would be created.
Symptoms of Code P2098
It is not unusual for diagnostic fault code P2098 to be accompanied by a few secondary symptoms of varying severity. In many situations, the identification of symptoms is the first step toward a sound diagnosis.
The following are several symptoms commonly associated with DTC P2098.
- Check engine light
- Erratic idle
- Reduced performance
- Multiple cylinder misfires
- Reduced fuel economy
- Superheating of internal catalyst media
Causes of Code P2098
There are many reasons Diagnostic Fault Code, or DTC “P2098” can happen and some of them can certainly be tricky to diagnose.
Those who know about these things are probably less “likely” to take the time to properly diagnose the issue you are having as quickly as possible.
Next is a list of the most common culprits when it comes to DTC-P2098.
- Upstream exhaust leaks
- Vacuum leaks
- A Malfunctioning MAP
- A Malfunctioning MAF
- Inconsistent upstream O2 sensor readings
- Damaged post-catalyst O2 sensor wiring
- PCM/ECM Failure
Is Code P2098 Serious?
Diagnostic code P2098 is an O2 sensor fault and will normally not be a drivability issue. You will still likely have the ability to drive. Having said that, code P2098 is not an issue to ignore, as the symptoms that stem from P2098 will most likely include a dramatic loss of engine performance.
Next, just as an aside, a true post-catalyst lean condition typically will pose an eventual problem to the catalytic converter itself. If a lean condition is allowed to persist, the catalyst will eventually become overheated, and once the substrate has burned through or the substrate has become compromised, then failure of the catalyst is guaranteed.
Replacement catalytic converters are not cheap to buy or have installed, and you certainly do not want to be driving a car without a catalytic converter.
In any case, you should try to address the cause of your P2098 sooner rather than later. This manner of thinking can reduce the chances that you will need to deal with secondary component fallout, especially related to catalyst concerns.
If you do not feel comfortable identifying and fixing the cause of your P2098 issue, then you should seek professional help as soon as you can.
How to Fix Code P2098
The following can be used when attempting to fix your P2098 diagnostic fault. Also, it is good practice to always consult factory-specific service literature for your specific vehicle before beginning any work.
#1. Check for Additional DTCs.
Before starting to diagnose the DTC P2098 fault, you should check to see if there are any additional diagnostic trouble codes present with a good OBD-II scan tool (I would recommend one of these).
If there are any other faults present, they should all be correctly diagnosed before moving on.
#2. Inspect ALL O2 Sensors.
The first item to do is to perform a visual inspection of the vehicle’s O2 sensors. This includes looking at the wiring and the plugs to each sensor. Since P2098 is a comparative fault, we will be checking them all.
#3. Check Feedback Data.
If you have a scan tool that does this, you will want to first check the feedback from the O2 sensors. Have an assistant drive the vehicle, then watch and check feedback from the O2 sensors. Graph the feedback if that’s an option.
While monitoring the feedback for each O2 sensor, you are looking for anything that skews out of range defined by the manufacturer. The O2 sensor will need to be replaced if they have incorrect or invalid feedback.
#4. Check MAP/MAF Sensor Feedback.
Check that the feedback from both the MAF and MAP sensors lies within the range specified by the manufacturer. If any value is outside of spec, then we will be troubleshooting each sensor/circuit, using the outlined procedures by the manufacturer.
#5. Check for Vacuum Leaks.
Using a smoke machine (for automotive-related applications specifically), make sure all vacuum systems or hoses on the vehicle are not leaking.
As an alternative method with a much more limited level of precision, you can utilize an unlit propane torch during the same steps to sense any RPM increase (assuming no combustion takes place in the circuit). All vacuum leaks need to be repaired before any further steps are taken.
#6. Check for any exhaust leaks upstream of the catalyst.
You will want to find, whenever possible, and repair any exhaust leaks occurring pre-catalyst, be it through visual inspection or the previously mentioned smoke machine. You cannot proceed until satisfied there are no exhaust leaks.
#7. Troubleshoot the feedback circuit.
If all of the above steps have been taken with no success, you will need to troubleshoot the feedback circuit of the bank #2 post-catalyst O2 sensor. Please do so according to the manufacturer-specific service procedures to avoid wrongfully condemning the vehicle’s PCM/ECM.