P219B Bank 2 Air/Fuel Ratio Imbalance (2022)

OBD-II Trouble Code Technical Description

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P219B Bank 2 Air/Fuel Ratio Imbalance (1)
Stephen Darby
ASE Certified Technician

Bank 2 Air/Fuel Ratio Imbalance

What does that mean?

This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Toyota, Dodge, Ford, Honda, Jeep, Chevy / Chevrolet, GMC, Ram, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain.

When a code P219B is stored, it means that the powertrain control module (PCM) has detected an air to fuel ratio imbalance for the bank of the engine which does not contain the number one cylinder.

In order to monitor the air to fuel ratio for each engine bank, the PCM uses data input from heated exhaust oxygen sensors (sometimes called air fuel sensors).

(Video) 2016 Honda Pilot Code P219B Bank 2 Air Fuel Ratio Imbalance / Diagnosis and Repair Part 1

Each oxygen sensor is constructed using a zirconium dioxide sensing element situated in the center of a vented steel housing. Tiny electrodes (usually of platinum) attach the sensing element to wire leads in the oxygen sensor harness connector and the connector plugs into the controller area network (CAN) which connects the oxygen sensor wiring harness to the PCM connector.

Each oxygen sensor is threaded (or studded) into an exhaust pipe. It is situated so the the sensing element is near the center of the pipe. As spent exhaust gases exit the combustion chamber (via the exhaust manifold) and continue through the exhaust system (including catalytic converters), they flow over the oxygen sensors. Exhaust gases enter the oxygen sensor through specially designed vent holes in the steel housing and swirl around the sensing element. Swirling ambient air is drawn through wire lead cavities in the sensor housing in order to fill a tiny chamber in the middle of the sensor. The air (in the tiny chamber) is then heated. This forces the oxygen ions to produce energy that is recognized by the PCM as voltage.

Variations between the number of oxygen ions in ambient air (drawn into the O2 sensor), and the number of oxygen molecules in the exhaust, cause the oxygen ions inside the O2 sensor to bounce from one platinum layer to the other, very swiftly and repetitively. As the surging oxygen ions shift between platinum layers, variations in oxygen sensor output voltage occur. The PCM sees these variations in oxygen sensor output voltage as changes in exhaust oxygen concentration. Voltage signal outputs from the oxygen sensors are lower when more oxygen is present in the exhaust (lean condition) and higher when less oxygen is present in the exhaust (rich condition).

If the PCM detects an imbalance in the air to fuel ratio for a particular bank of the engine, a code P219B will be stored and a malfunction indicator lamp (MIL) may be illuminated. Most vehicles will require multiple ignition cycles (with a failure) for MIL illumination.

A typical oxygen sensor:
P219B Bank 2 Air/Fuel Ratio Imbalance (2)


What is the severity of this DTC?

An incorrect air to fuel ratio may be the result of insufficient fuel or excessive air (vacuum). A code P219B should be categorized as severe and rectified as quickly as possible.

What are some of the symptoms of the code?

Symptoms of a P219B trouble code may include:

  • Diminished fuel efficiency
  • A lack of general engine performance
  • Stored misfire codes or lean/rich exhaust codes
  • Service engine soon lamp illumination

What are some of the common causes of the code?

Causes for this code may include:

  • Engine vacuum leak (large)
  • Defective oxygen sensor/s
  • Burnt, chafed, broken, or disconnected wiring and/or connectors
  • Engine exhaust leaks
  • A faulty mass air flow or manifold air pressure sensor
  • Bad fuel pump or clogged fuel filter

What are some P219B troubleshooting steps?

All misfire codes, throttle position sensor codes, manifold air pressure codes, and mass air flow sensor codes should be addressed before attempting to diagnose a code P219B. The engine should also be running smoothly and efficiently. If it is determined that either a rich or lean condition exists (with the engine), this must be repaired as it may be the cause of the P219B being stored.

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of reliable vehicle information in order to accurately diagnose a code P219B.

(Video) 2015 GM Truck 5.3 Stumble, P0300, P219B Codes Diagnosis Part 1.

You may save yourself time by searching for technical service bulletins (TSB) that replicate the code stored, vehicle (year, make, model, and engine), and symptoms exhibited. This information may be found in your vehicle information source. If you find the right TSB, it could yield a speedy solution to your diagnosis.

After you connect the scanner to the vehicle diagnostic port and retrieve all stored codes and pertinent freeze frame data, write the information down (in case the code proves to be an intermittent one). After that, clear the codes and test drive the vehicle until one of two things happens; the code is restored or the PCM enters readiness mode.

The code may actually be more difficult to diagnose if the PCM enters readiness mode at this point, because the code is intermittent. The condition which caused the P219B to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, continue with the diagnosis.

You may obtain connector face views, connector pinout charts, component locator charts, wiring diagrams, and diagnostic flow charts (pertaining to the code and vehicle in question) using your source of vehicle information.

Perform a visual inspection of related wiring and connectors. Repair or replace wiring that has been cut, burned, or damaged.

(Video) What is P219B Engine Code [Quick Guide]

If the engine is running smoothly and the code P219B continues to be reset, start the engine and allow it to reach normal operating temperature. Allow the engine to idle (with the transmission in neutral or park). With the scanner connected to the vehicle diagnostic port, observe oxygen sensor input data on the data stream. Narrow the scope of the data stream to include only pertinent data and you will get a faster response.

If the oxygen sensors are functioning normally, voltage on pre-cat oxygen sensors will cycle continuously between 1 and 900-millivolts once the PCM enters closed loop operation. Post-cat sensors will cycle between 1 and 900-millivolts as well but they will settle at a certain point and remain relatively stable) compared to the pre-cat sensors). Oxygen sensors which fail to cycle adequately should be considered defective if the engine is in good working order.

  • In most cases, you will rectify this code by correcting a rich or lean running engine

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Need more help with a P219B code?

If you still need help regarding the P219B trouble code, please postyour question in our FREE car repair forums.

(Video) ⫷ p219a, p219b, p0171, p0174, Air / fuel imbalance / Lean condition / podcast ⫸

NOTE: This information is presented for information purposes only.It is not intended as repair advice and we are not responsible for any actionsyou take on any vehicle. All information on this site is copyright protected.


What is an air fuel ratio imbalance? ›

Air-fuel ratio cylinder imbalance is a condition where the air-fuel ratio in one or more cylinders is different than the other cylinders. When air-fuel ratio cylinder imbalance occurs in one or more cylinders the fuel delivery system is unable to maintain a proper vehicle emission level.

What causes air fuel ratio problems? ›

Problems with air fuel ratio sensors are common. Often a sensor gets contaminated or simply fails. In some cars, the heating element inside the sensor can stop working and cause the malfunction. For example, in many Toyota and Honda cars the code P0135 may be caused by a failed heating element inside the sensor.

How do you test air and fuel mixture? ›

How is it measured? The air/fuel mixture can be analyzed by looking at O2 Sensor data from your ECU. Another way to monitor your air/fuel mixture is with an Air/Fuel Ratio Gauge. Many AFR gauges also display lambda value.

What is the perfect air/fuel ratio? ›

The stoichiometric mixture for a gasoline engine is the ideal ratio of air to fuel that burns all fuel with no excess air. For gasoline fuel, the stoichiometric air–fuel mixture is about 14.7:1 i.e. for every one gram of fuel, 14.7 grams of air are required.

What is a good air-fuel ratio at idle? ›

The 14.7:1 ratio is perfect for idling and light throttle cruising conditions as it's the most efficient mixture possible, meaning the best fuel economy and lowest emissions.

How do I fix my P219B code? ›

How To Correct P219B Bank 2 Air/Fuel Ratio Imbalance
  1. Rehabilitate the defaults in the oxygen sensor/s.
  2. The malfunctioning fuel pump should be repaired or replaced as per the need.
  3. Make sure to mend the blocked fuel filter.
  4. It is essential to fix the leakage in the engine vacuum.
  5. Repair the leakages in the engine exhaust.
2 Jun 2022

What does a fuel imbalance mean? ›

A fuel imbalance is when the amount of fuel between the left and right fuel tanks in the wings of an aircraft is unequal and could affect the plane's handling, according to Boeing.

How serious is P219A? ›

The trouble code P219A can be defined as Bank 1 Air/Fuel Ratio Imbalance. This code is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made from 1996 up to present.

What sensors control air fuel mixture? ›

An air-fuel ratio meter monitors the air–fuel ratio of an internal combustion engine. Also called air–fuel ratio gauge, air–fuel meter, or air–fuel gauge, it reads the voltage output of an oxygen sensor, sometimes also called AFR sensor or lambda sensor.

What kills an oxygen sensor? ›

MALFUNCTIONING AND FAILED SENSORS Oxygen sensors can fail when the sensor's ceramic element is exposed to certain types of silicone compounds or when an oil-burning engine leads to the sensor becoming oil-fouled. Also, a small amount of tetra-ethyl lead in the gasoline can kill an oxygen sensor.

What controls the air fuel mixture in a car? ›

The primary sensor for real-time adjustment to air/fuel mixture is the upstream oxygen sensor. The sensor generates a RICH or LEAN signal that the PCM uses to constantly adjust the fuel mixture.

What happens when air-fuel ratio is too rich? ›

Too much fuel in the air/fuel mixture can make your vehicle surge, sputter, or even stall. For example, if the carburetor is set way too rich, it will push enough gas through to the combustion chamber and flood the engine. Your engine power might lag if the engine is being flooded while you're driving, as well.

What AFR is too rich? ›


Most stock to slightly modified engines will run just fine at an AFR of 15 and yield better MPG. If you prefer better PERFORMANCE then we suggest to run an AFR of 14 or even richer to around 13.

How do I know if my pilot jet is too rich? ›

If the pilot circuit is rich, the engine will have a rough idle or may not return to idle without "blipping" the throttle. You may also notice a distinct smell of raw fuel and some eye irritation from the exhaust.

Is it better to run lean or rich? ›

TLDR – running just a little lean could improve fuel economy and give extra power. However, run too lean and you risk engine failure because the engine runs too hot. Whereas running rich can waste fuel and increase pollution but will not damage the engine. You ideally want to run at the perfect ratio of 14.7:1.

Which is better lean or rich mixture? ›

The key difference between lean and rich fuel mixture is that we use a lean mixture for maximum efficiency while we use a rich mixture for maximum power in an engine. We use the terms lean and rich fuel mixtures to describe combustion processes in engines and industrial furnaces.

Which engine has the highest air/fuel ratio? ›

111. Which engine has the highest air fuel ratio ? (D) Gas turbine.

How lean is too lean air/fuel ratio? ›

Generally, the engine is considered to be running too lean when fuel trim is above 10% (with the engine running in closed-loop mode). If fuel trim is below -10%, the engine is typically considered to be running rich.

What is the ideal air-fuel ratio for a spark ignition engine? ›

Spark ignition (SI) engines usually run on gasoline (petrol) fuel. The AFR of the SI engines varies within the range 12:1 (rich) to 20:1 (lean), depending on the operating condition of the engine (temperature, speed, load, etc.).
Air fuel ratio for different fuels.
FuelChemical formulaAFR
7 more rows

What is P0174? ›

The P0174 engine code indicates that your car's air-fuel ratio is too lean. The gas in your car has to be mixed with oxygen before it can combust and power your vehicle. When the air and gas are present in the right ratio (known as the stoichiometric ratio or “stoich”), the mixture burns completely.

What is a P0151 code? ›

What the P0151 code means. P0151 is the OBD-II generic code indicating the O2 sensor for bank 2 sensor 1 fails to increase the voltage output above . 21 volts, indicating excessive oxygen in the exhaust.

What does P050D code mean? ›

What Does the P050D Code Mean? Code P050D is a generic trouble code related to a rough engine idle during cold start. Diagnostic trouble code (DTC) P050D stands for “Cold Start Rough Idle.” The PCM monitors your engine's RPM using signals from the (CKP) crankshaft position sensor and the camshaft position (CMP).

Can a fuel imbalance cause a plane to crash? ›

No fuel pressure means no fuel is being fed into the engine. If the issue is resolvable, such as a faulty pump, the pilot will use the auxiliaries to maintain flight. If the plane goes into fuel starvation, it could result in an engine failure, forced landing, or even a stall and crash.

How long does it take to Defuel a plane? ›

Fuel jettisoning systems can dump thousands of pounds a second. Most can get a plane back down to its max landing weight in 15 minutes or less, and it's usually as easy as flipping a switch in the cockpit.

How does the center of gravity affect the balance of an airplane? ›

Much like an aircraft, when the centre of gravity of the aircraft is located too far off the range, the aircraft will be heavier on one side than the other and the pilot may lose control of the aircraft. Nose-heaviness and/or tail-heaviness are all caused by longitudinal unbalance of the aircraft.

How do I fix code P1174? ›

In this case, the fix is as simple as replacing your O2 sensor, which costs about $50 and can be DIY'd easily. After replacing your O2 sensor, if you continue to receive P1174 or P1175 engine codes, you should check your MAF and try cleaning or replacing that.

Is air-fuel ratio sensor same as O2 sensor? ›

An air/fuel sensor can read a much wider and leaner range of fuel mixtures than a conventional O2 sensor. That's why they're also called “wideband” O2 sensors. Another difference is that A/F sensors don't produce a voltage signal that suddenly changes on either side of Lambda when the air/fuel goes rich or lean.

How do you clean an air-fuel sensor? ›

How to Clean OXYGEN Sensors [Easy Way] - YouTube

How do you know which O2 sensor to replace? ›

It is best to replace O2 sensors in pairs. For example, if you replace the downstream left sensor, you should also replace the downstream right. However, on most vehicles produced since 1996, replacing one sensor (especially the front engine monitoring sensor) will cause the ECU to set a code for the other sensors.

Can you bypass oxygen sensors? ›

While you can bypass an Oxygen sensor with the help of a dummy O2 sensor, it's not always the best option. In some cases, it could be illegal and other times it can mess with the performance of the vehicle. However, it's easy to do, requiring you to swap the defective sensor with a dummy.

What happens if you disconnect oxygen sensor? ›

With the O2 sensor removed, your ECU can no longer calculate how much fuel should be injected. The ECU will fallback to its default value and always inject the same amount of fuel every time. This could cause either low performance or horrible fuel economy.

Can you repair an oxygen sensor? ›

Typically, you cannot repair a faulty O2 sensor. It must be replaced because of the technology and materials in its housing. There are some DIY places that will tell you how to clean the sensor to get a few more miles out of it, but you're only delaying the inevitable.

How do I increase the airflow in my engine? ›

Upgrading from a stock filter to a cold air intake is one of the best and easiest ways to increase horsepower. They have special filters that increase the surface area that pulls the air into your engine. Not only do they increase the amount of air that's taken in, but they do so while the air is still cool.

Is backfiring lean or rich? ›

Lean Air/Fuel Mixture

Not only can a rich air/fuel ratio cause a backfire, a mixture that doesn't have enough gasoline can cause a backfire, too. A "lean" mixture is one that doesn't have enough fuel, and too much air.

What is the difference between air-fuel ratio sensor and oxygen sensor? ›

the air/fuel ratio sensor provides a higher level of sensitivity than the traditional oxygen sensor. This allows the EMS to respond to the needs of the engine with higher accuracy, which enables the fuel to burn more efficiently, therefore producing lower emissions and increasing the vehicle's fuel economy.

How do you fix rich fuel mixture? ›

How to fix a car running rich
  1. Run full diagnostics to find the exact cause of the problem.
  2. Change the car's air duct flap.
  3. Clean the mass airflow sensor.
  4. Vacuum hoses and lines.
  5. Change faulty spark plugs.
  6. Review the oxygen sensor.
  7. Replace the catalytic converter.
  8. Fix the engine.
15 Mar 2022

How do I fix code p1135? ›

The first step in diagnosis is visually checking the wiring for the harness to make sure no wires are damaged. Next, check the connections to make sure nothing has pulled loose. From there, replacement of the sensor is your best bet; a bad sensor is almost always the cause of this code and is a very common occurrence.

What causes a car to run to lean? ›

Your engine runs lean if your air-to-fuel mixture is too light - this means that the fuel in your ignition chamber is being igniting with too much air or too little fuel. Because your engine is running on less fuel than it should, it is running “lean.”

Can you clean an air fuel sensor? ›

No car manufacturer supports cleaning sensors. In fact, you always risk voiding a warranty if you attempt to clean a sensor and something goes wrong later. If you find that your car has a faulty oxygen sensor, here's how you can replace it.

What should rear O2 sensor read? ›

The voltage generated from the O2 sensor should be from 0.1V to 0.9V, with 0.9V on the rich side and 0.1V on the lean side. If your readings are within this range, the O2 sensor is functioning properly.

How do I know if my wideband sensor is bad? ›

AEM Wideband Sensor Test - YouTube

Is backfiring lean or rich? ›

Lean Air/Fuel Mixture

Not only can a rich air/fuel ratio cause a backfire, a mixture that doesn't have enough gasoline can cause a backfire, too. A "lean" mixture is one that doesn't have enough fuel, and too much air.

Will a vacuum leak cause car to run rich? ›

Yes, it will make your car run rich, not lean. The MAF doesn't read that air coming in since it was leaked in after the MAF. The ECU has a reading for how much air went into that combustion cycle.

What sensors affect fuel trim? ›

The oxygen sensors monitor the accuracy of the computer's fuel trim strategy. The oxygen sensor is located in the exhaust and monitors the amount of unburned oxygen in the exhaust. This is an indicator of the fuel mixture integrity.

What causes P1135 code? ›

DTC P1135 on Lexus vehicles stands for “Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 1 Sensor 1).” This trouble code sets when the powertrain control module (PCM) has detected a malfunction in the heater circuit of the air/fuel ratio sensor.

Where is the air-fuel ratio sensor located? ›

Where is it Located? The air-fuel ratio sensor is located in either the exhaust manifold or the front exhaust pipe. It measures the amount of air in your exhaust and uses that information to determine your current air-fuel ratio.

What does engine code P1135 mean? ›

What is P1135 Engine Code [Quick Guide] - YouTube

Can a bad O2 sensor cause a lean condition? ›

Yes the O2 sensor can cause the vehicle to run lean. What the O2 sensor does is read the amount of air entering the engine and sends that information to the computer, the computer reads this information and determines how much fuel the engine needs.

Is it better to run lean or rich? ›

Q: Is it better to run the too lean or rich engines? An engine running slightly rich will give more power, but running lean will cause catastrophic engine damage. Running too rich can also cause severe damage to your engine.

What are the symptoms of a vacuum leak? ›

Here are four signs that your vehicle has a vacuum leak.
  • Sporadic Idling. A vacuum leak introduces excess air into the engine, and this directly affects how your engine runs. ...
  • Engine Hesitation. Your engine trouble will not be limited to your idling if you have a leak. ...
  • Vacuum Sounds. ...
  • 4 Check Engine Warning.
1 Mar 2021


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