Fault code P00BF is called “Mass or Volume Air Flow “B” Circuit Range/Performance – Air Flow Too High” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P00BF
This Diagnostic Trouble Code (DTC) is a generic powertrain code. Error P00BF is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.
The mass air flow sensor (MAF) is a sensor installed in the air intake path of the vehicle engine after the air filter, and is used to measure the volume and density of the air drawn into the engine. The mass flow sensor itself measures only a portion of the incoming air, and this value is used to calculate the total volume and density of the intake air.
The Powertrain Control Module (PCM) uses this reading along with other sensor parameters to ensure proper fuel delivery at all times for optimum power and fuel economy.
Normally, this diagnostic trouble code (DTC) P00BF means there is a problem with the “B” sensor or mass air flow (MAF) circuit. The PCM detects that the actual mass air flow sensor frequency signal is not within the specified expected range of the calculated MAF value. In this case, the error means that the air flow rate is too high.
Some mass airflow sensors also include an air temperature sensor, which is another value the PCM uses for optimal engine performance.
Symptoms of vehicle malfunctions
The main signal that an error P00BF has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- Check engine light on the control panel is on.
- Jerking / ignition skips.
- Black smoke coming out of the exhaust pipe.
- Engine stalls or fails to start.
- Loss of power.
- Lambda probe related errors are generated.
Factors that can cause this error code
The error code P00BF can mean that one or more of the following problems have occurred:
- Mass air flow sensor (MAF) may be dirty.
- Defective mass air flow sensor.
- Leakage of intake air.
- Electrical harness or connectors to the mass air flow sensor (MAF) may be worn (breakage, short circuit, wear, poor connection, etc.).
- The fuel vapor vent valve from the tank is damaged and is introducing extra air into the intake port.
- Worn or damaged gasket under throttle valve or intake manifold.
- Worn vacuum lines.
- Clogged catalytic converter (on some models).
Note, there may be other trouble codes along with error P00BF. You may have misfire codes or O₂ sensor codes. Therefore, it is important to get the “big picture” of how the systems work together and affect each other when diagnosing.
How to fix or reset OBD-2 code P00BF
Some suggested steps for troubleshooting and fix the error code P00BF:
- Check all cables and associated connectors leading to the mass air flow sensor (MAF). Make sure they are not broken or frayed. Repair or replace if necessary.
- Check for air leaks in the intake system. Correct the problem if you find a leak.
- Inspect the mass air flow sensor (MAF) power supply line for dirt and dust.
- If the air filter is dirty, it can be replaced.
- There are air intake systems with a screen, in which case you need to make sure it is clean.
- This code may be caused by high resistance in the ground circuit of the absolute pressure sensor (MAP).
- Replace the mass air flow sensor.
Diagnose and repair of problems
Starting the diagnosis of P00BF malfunction, check all wiring as well as the connectors of the mass air flow sensor. Make sure they are intact, not frayed or broken. The wiring should not be too close to the wires / ignition coils, relays, etc.
Visually check for obvious air leaks in the air intake system. Also lack of vacuum on the MAP sensor can cause this fault code. It’s worth checking the air filter, if it’s dirty, it needs to be replaced. If there is a screen in the air intake system, make sure it is clean.
Carefully inspect the mass air flow sensor to see impurities such as dirt, dust, oil, etc. Clean thoroughly with MAF cleaning spray, this is usually a good diagnostic/repair step done on your own.
Low minimum air flow through the sensor port can cause this fault code to set at idle or during deceleration. Check for vacuum leaks after the mass air flow sensor.
Use a diagnostic tool to monitor the mass air flow sensor values, in real time. Check the Technical Service Bulletins (TSB) for your specific make/model for known problems with your vehicle.
Atmospheric pressure (BARO), which is used to calculate the predicted MAF value, is initially based on the MAP sensor when the key is on. High resistance in the MAP sensor ground circuit can cause this trouble code to set.
Perform an exhaust backpressure test to determine if the catalytic converter is clogged.
If you do need to replace the mass air flow sensor. It is recommended that you use the original OEM sensor from the manufacturer. Not to buy replacement parts of dubious origin.
Using a reusable oil air filter can cause a P00BF error code if it is overly lubricated. Oil can get on the thin wire or film inside the mass air flow sensor and contaminate it. Use something like MAF cleaning spray to clean it in these situations.
On which vehicles does this problem occur most frequently
Fault code P00BF can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- BMW
- Ford
- Jaguar
- Land Rover (Range Rover)
- Mazda
- Mini
- Volvo
Fault code P00BF can sometimes be found with other errors. The most common are the following: P00BC, P00BD, P00BE.
