Symptoms
The symptoms of a P2098 code vary depending on the component or system causing the fuel trim disturbance. Not all will be present at the same time.
- Malfunction Indicator Lamp (MIL) illuminated with P2098 DTC stored
- Rough idle
- Poor fuel economy
- Poor acceleration
- Misfire
- Hot cherry red catalytic converter
- Possible engine knock (detonation / pre-ignition)
- Additional codes associated with P2098
Potential Causes
Causes
of this DTC may include:
- Low fuel pressure caused by a clogged filter, failing fuel pump, faulty fuel pressure regulator, or clogged or leaking injectors.
- Engine running poorly due to misfiring spark plugs. Many engines have misfire codes to indicate the affected cylinder, such as P0307 for cylinder number 7.
- A significant vacuum leak would allow a massive amount of unmetered air into the intake manifold, resulting in a mixture that is too lean.
- A significant air leak at or near the number one oxygen sensor would also cause a lean mixture.
- A plugged catalytic converter will cause many drivability issues and set this code. A severely clogged converter will prevent the engine RPM from increasing under load. Look for a code such as P0421 – catalytic converter efficiency below threshold if the converter indicates a faulty converter.
- A faulty oxygen sensor. This will set a code itself; however, an oxygen sensor code does not automatically condemn the sensor. The code simply means the sensor’s signal was not within specifications. An air leak or one of the items above will cause an incorrect signal. There are numerous O2 codes related to O2 performance that give a clue to the problematic area.
The Mass Air Flow (MAF) sensor will also cause this problem. It would be accompanied by a code such as P0100 – Mass Air Flow Circuit Malfunction. The MAF sensor is a hot wire that detects the volume of air entering the intake manifold. The computer uses this information to control the fuel mixture. - Rusted exhaust systems, cracked exhaust manifolds, or damaged or missing gaskets or donuts will cause air leaks.
- To make a point about cause and effect on vehicles, consider this scenario. A simple air leak upstream of the number one oxygen sensor adds extra air to the mixture not measured by the computer. The oxygen sensor reports a lean mixture due to the unmetered air.
Immediately, the computer enriches the mixture to prevent a lean mixture from causing damage due to knocking, among other factors. The unnecessarily rich mixture begins to foul the spark plugs, contaminate the oil, overheat the converter, and reduce fuel economy. These are just a few of the things that happen under these circumstances.
Diagnostic and Repair Procedures
It is wise to go online and acquire the Technical Service Bulletins (TSBs) associated with these codes and a description. Although all vehicles suffer from similar causes, some may have a service history of problems with a particular component associated with this code.
If you have access to an advanced diagnostic scan tool such as a Tech II or Snap-On Vantage, it will save you a lot of time. The scanner has the ability to graphically represent and display real-time numerical information from each sensor’s performance. It will show the oxygen sensors in operation to easily recognize one that is malfunctioning.
Jeeps and some Chrysler products seem to suffer from poor electrical connectors, so inspect them carefully. Additionally, Jeeps have had several PCM updates on recent models. Reprogramming the updates along with replacing the oxygen sensor for any reason is covered by the 8-year/80,000-mile warranty. To check if the update has been done, look beside or behind the battery and there will be a serial number with the computer update date. If it hasn’t been done, it is free for the period mentioned above.
- Connect the code scanner to the OBD port under the dashboard. Turn the key to “On” with the engine off. Press the “Read” button and the codes will display. Record all additional codes on the attached code sheet. Focus your attention on these codes first.
- In the absence of additional codes matching P2096 or P2098, test drive the vehicle and look for the telltale symptoms. Fuel contamination will cause this code. Refill with a higher octane fuel.
- If the vehicle displays very little power and struggles to accelerate, look underneath the vehicle with the engine running. A clogged converter will typically glow red.
- Check the engine for vacuum leaks between the Mass Air Flow sensor and the intake manifold. Often, leaks sound like a whistle. Repair the leaks and clear the code.
- If the engine is misfiring and there is no code, determine which cylinder is misfiring. If the exhaust manifold is visible, spray or pour a small amount of water on each cylinder’s exhaust port. The water will evaporate immediately on the good cylinders and slowly on the misfiring cylinder. If this cannot be done, remove the spark plugs and check their condition.
- Look at the spark plug wires to ensure they are not burnt or resting on the exhaust.
- Inspect the exhaust system. Look for rust holes, missing gaskets, cracks, or looseness. Lift the vehicle and with a 7/8-inch wrench, ensure the oxygen sensor is tight. Inspect the wiring harness and connector.
- If a code for the Mass Air Flow sensor appears, check its connector. If it is okay, replace the MAF sensor.
- Replace the oxygen sensor that is downstream of the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if an oxygen sensor code indicates “heater circuit malfunction,” the sensor is most likely faulty.
