Technical Description of OBD-II Trouble Code
The barometric pressure sensor B is indicating a low reading.
What does that mean?
This is a generic diagnostic trouble code (DTC) that applies to OBD-II vehicles. It can affect various vehicle makes and models such as Chevy, Mazda, Volvo, Acura, Honda, BMW, Isuzu, Mercedes Benz, Cadillac, Hyundai, Saab, Ford, GMC, etc. The specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
Most Engine Control Modules (ECMs) rely on multiple measurements to maintain an optimal air to fuel ratio for the engine. The ideal air/fuel ratio is known as the “stoichiometric” mixture, which is 14.7 parts air to one part fuel. The ECM monitors various values such as air flow, coolant temperature, engine speed, load demand, atmospheric temperature, etc., to keep the fuel mixture as close to stoichiometric as possible. Some engine management systems prioritize intake and atmospheric pressures to optimize the mixture.
In some cases, barometric air pressure (BAP) sensors are used alongside manifold absolute pressure (MAP) sensors. BAP sensors measure atmospheric pressure, which is crucial for determining fuel mixtures. The ECM compares atmospheric pressures to intake manifold pressures to accurately adjust the fuel mixture based on the driver’s needs. Altitude plays a significant role in diagnosing BAPs, as symptoms may worsen or improve depending on the location, especially in mountainous areas.
When a letter is included in an OBD2 fault code’s description (such as “B” in this case), it often indicates a specific aspect of the system being addressed, such as different banks, sensors, circuits, connectors, etc. In this case, the letter “B” is likely used to identify the specific sensor being referred to. Multiple barometric sensors are often used to ensure accurate readings and assist in fuel management. Additionally, these sensors help identify faults within the sensors or circuits. Consult your service manual for detailed information on letter specifications for your particular vehicle.
The ECM sets the P222C code when it detects a low electrical value or reading from the Barometric pressure (BAP) “B” sensor or its circuit(s).
What is the severity of this DTC?
The severity of this DTC is moderately high. It is important to address this issue promptly to maintain efficient engine operation. If a fault can directly impact critical values like air/fuel ratios and is actively present, it is advisable not to operate the vehicle to prevent potential engine damage. However, if you have already driven the vehicle with the fault active, there may not be immediate cause for concern. Nevertheless, if left unattended, this fault could lead to expensive internal engine damage in the future.
What are some of the symptoms of the code?
Symptoms of a P222C trouble code may include:
- Lack of engine power and performance (or limited)
- Engine misfiring
- Abnormal engine noise(s)
- Fuel smell
- Decrease in fuel economy
- Decreased throttle responsiveness
What are some of the common causes of the code?
Possible causes for the P222C code include:
- Defective or damaged Barometric Air Pressure (BAP) sensor
- Defective or damaged electrical connector
- Wiring issues (e.g., open, short, corrosion)
- Electrical short (internal or mechanical)
- Loose electrical connection
- Heat damage
- Mechanical malfunction causing altered BAP readings
- Engine Control Module (ECM) issue
What are some P222C troubleshooting steps?
Basic Step #1
Locate the Barometric Air Pressure (BAP) sensor on your specific vehicle. The sensor’s location can vary significantly, so it is crucial to find the correct sensor. Inspect the BAP sensor for any physical damage, considering factors such as high heat areas, engine vibrations, exposure to elements/road debris, etc.
Basic Step #2
Ensure that the connector on the sensor is properly seated to establish a good electrical connection. If the sensor is located on the engine, vibrations may cause connections to loosen or become physically damaged.
NOTE: Remember to disconnect the battery before disconnecting any sensors to avoid damaging electrical spikes. If you are uncomfortable or have limited electrical knowledge, it is recommended to have your vehicle towed or driven to a reputable repair facility.
Basic Step #3
Check for any obstructions that may be affecting the sensor’s readings. Accurate readings are crucial for optimal engine performance in fuel management systems.
Basic Step #4
Using a multimeter, follow manufacturer-specific diagnostic procedures to measure the desired electrical values for the barometric air pressure sensor. Disconnect the connector from the sensor to access the pins and compare the readings with the specified range. Any values outside the range indicate a defective sensor, which should be replaced following proper removal and installation procedures.
