Technical Description of OBD-II Trouble Code
Imbalance in Air/Fuel Ratio for Bank 2
What does that signify?
This is a generic diagnostic trouble code (DTC) that is applicable to many OBD-II vehicles (1996-newer). This includes vehicles from Toyota, Dodge, Ford, Honda, Jeep, Chevy / Chevrolet, GMC, Ram, etc. While it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain.
When code P219B is stored, it indicates that the powertrain control module (PCM) has detected an imbalance in the air to fuel ratio for the bank of the engine that does not contain the number one cylinder.
To monitor the air to fuel ratio for each engine bank, the PCM utilizes data input from heated exhaust oxygen sensors (sometimes referred to as air fuel sensors).
Each oxygen sensor consists of a zirconium dioxide sensing element located in the center of a vented steel housing. The sensing element is attached to wire leads in the oxygen sensor harness connector using tiny platinum electrodes. The connector is then plugged 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, positioned so that the sensing element is near the center of the pipe. As exhaust gases exit the combustion chamber (via the exhaust manifold) and flow through the exhaust system (including catalytic converters), they pass over the oxygen sensors. The 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 to fill a tiny chamber in the middle of the sensor. The air in the chamber is then heated, causing the oxygen ions to produce voltage that is recognized by the PCM as energy.
Variations in the number of oxygen ions in ambient air (drawn into the O2 sensor) compared to the number of oxygen molecules in the exhaust cause the oxygen ions inside the O2 sensor to rapidly bounce between platinum layers. These variations in oxygen sensor output voltage are detected by the PCM as changes in exhaust oxygen concentration. The voltage signal outputs from the oxygen sensors are lower when there is more oxygen in the exhaust (lean condition) and higher when there is less oxygen in the exhaust (rich condition).
If the PCM detects an imbalance in the air to fuel ratio for a specific bank of the engine, it will store code P219B and may illuminate the malfunction indicator lamp (MIL). Most vehicles will require multiple ignition cycles with a failure for the MIL to illuminate.
A typical oxygen sensor:
What is the severity of this DTC?
An incorrect air to fuel ratio may be caused by insufficient fuel or excessive air (vacuum). Code P219B should be considered severe and addressed as soon as possible.
What are some of the symptoms of the code?
Symptoms of a P219B trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P219B troubleshooting steps?
Prior to diagnosing a code P219B, address all misfire codes, throttle position sensor codes, manifold air pressure codes, and mass air flow sensor codes. The engine should also be running smoothly and efficiently. If a rich or lean condition is determined to exist with the engine, it must be repaired as it may be the cause of the stored P219B code.
To accurately diagnose a code P219B, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information.
You can save time by searching for technical service bulletins (TSB) that match the stored code, vehicle (year, make, model, and engine), and exhibited symptoms. This information can be found in your vehicle information source. If you find the appropriate TSB, it may provide a quick solution to your diagnosis.
After connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and relevant freeze frame data, write down the information in case the code proves to be intermittent. Then, clear the codes and test drive the vehicle until one of two things occurs: the code is restored or the PCM enters readiness mode.
If the PCM enters readiness mode at this point, diagnosing the code may become more difficult because it is intermittent. The condition that 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 can obtain connector face views, connector pinout charts, component locator charts, wiring diagrams, and diagnostic flow charts specific to the code and vehicle in question from your source of vehicle information.
Perform a visual inspection of the related wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged.
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. Let the engine idle (with the transmission in neutral or park) and observe the oxygen sensor input data on the data stream using the scanner. Narrow the scope of the data stream to include only relevant data for a faster response.
If the oxygen sensors are functioning normally, voltage on the pre-oxygen sensors will continuously cycle between 1 and 900 millivolts once the PCM enters closed loop operation. Post sensors will also cycle between 1 and 900 millivolts, but they will settle at a certain point and remain relatively stable compared to the pre sensors. Oxygen sensors that fail to cycle adequately should be considered defective if the engine is in good working order.
