P2190 Code: System Too Rich Off Idle Bank 2

P2190 is a generic trouble code indicating a rich condition that exists above idle but not necessarily at idle.

What Does the P2190 Code Mean?

Diagnostic trouble code P2190 stands for “System Too Rich Off Idle Bank 2.” The code is set once the PCM detects a rich condition (or too much fuel). The code is logged once the PCM detects that the desired air-fuel ratio isn’t achieved. This code is assigned for Bank 2, the bank of cylinders that doesn’t include cylinder #1. Depending on the fuel system and vehicle manufacturer, this can be a mechanical or electrical circuit issue.

The P2190 code is logged in fuel-injected engines from most European and Asian manufacturers since 2010. This includes vehicles manufactured by Volkswagen, Audi, Mercedes, BMW/Mini, Hyundai, Mazda, Kia, Infiniti, and more.

P2190 on a Hyundai Santa Fe

The PCM detects the fuel trim value at idle under detecting conditions. Once the PCM detects that the average value exceeds the limit at a certain amount of time, it’ll trigger the code. The check engine light will usually turn on if the malfunction lasts two consecutive driving cycles.

More on How Oxygen Sensors Work

To help you understand the code better, it’s best to refresh your knowledge of how oxygen (O2) sensors work.

O2 sensors calculate the concentration of combustibles (or the amount of oxygen) in the exhaust gasses leaving the engine. O2 sensors were first used in the production of automobiles in the 1970s, and by the 1980s, they were widely used.

A low voltage signal from the oxygen sensor indicates that there is not enough oxygen in the exhaust, indicating that the engine is running rich. The PCM responds by decreasing the amount of fuel delivered to the engine.

A high voltage signal, on the other hand, indicates high oxygen content and warns that the engine is running lean, causing the PCM to increase fuel to compensate for the excess air.

If you need more clarity about P2190 and similar codes, you can read our technical discussion about fuel trims and “off idle.”

Note: The definition of the P2190 code can be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What Are the Common Causes of the P2190 Code?

• Bad O2 sensor
• Faulty MAF sensor (will affect BOTH banks)
• Malfunctioning PCM
• EVAP system concerns

What Are the Common Symptoms of the P2190 Code?

• Illuminated check engine light
• Lack of engine power
• Engine misfire
• Poor fuel economy

How to Diagnose the P2190 Code

Despite the fact that DTC P2190 is a generic trouble code, there is no universal fix for it. Several diagnostic procedures may be required depending on the make and model of the vehicle.

In addition to a scan tool, you’ll need specific tools and up-to-date technical information about your throttle position sensor. If you lack experience in these areas, you should leave vehicle repair and diagnosis to a reputable mechanic. Otherwise, you can investigate the root cause of the problem on your own.

How to Fix the P2190 Code

It can be difficult to resolve the P2190 error code, especially if you lack the necessary DIY and automotive knowledge. If this is the case, you should take your vehicle to a shop for repairs so that an expert can handle the situation.

If, on the other hand, you are confident that you can clear the error code on your own, make sure you have the appropriate repair manual nearby before you begin. You may also get vehicle-specific information by subscribing to an online repair database.

Fuel Trims and “Off Idle”

Using readings from oxygen sensors in the exhaust, the PCM adjusts the amount of fuel delivered to maintain the optimum 14.7 “stoichiometric” ratio that provides the most efficient fuel-air mixture for combustion and the cleanest possible pre-catalyst exhaust.

Remember that O2 sensors detect oxygen and not fuel. A misfiring cylinder will send unburned fuel and air through the exhaust. However, all the O2 sensor will detect is oxygen. The O2 sensor has no way to detect hydrocarbons (gasoline) or nitrogen (which is 78% of the atmosphere drawn through the engine). 

Remember that O2 sensors detect oxygen and not fuel. A misfiring cylinder will send unburned fuel and air through the exhaust. However, all the O2 sensor will detect is oxygen.

– Richard McCuistian, ASE Certified Master Automobile Technician

That being said, the O2 sensor’s input to the PCM will drive the fuel trims in the direction of subtracting fuel due to the perceived rich condition. And it happens very rapidly.

Short fuel trims react first, followed by long fuel trims, which correct more slowly and are part of the adaptive learning strategy.

“Lean” means an imbalance that the O2 sensor perceives as out of balance, with 14.7:1 being the target. That’s 14.7 parts air (by weight) to 1 part fuel (by weight), which is how engineers measure fuel and air in this context. By volume, an engine uses 9,000 gallons of air for every gallon of fuel.

“Off Idle” means the throttle is being applied. When the key is first turned to the ON position, the ECM/PCM stores the initial throttle reading as “closed throttle” or C/T on the scan tool. When the throttle position sensor voltage rises above the “closed throttle” threshold stored on that start cycle, the ECM/PCM considers that “off idle” or “part throttle” which will show as “P/T” on the scan tool.