What Does P00BF Mean?
The mass or volume air flow sensor on circuit 'B' is reporting airflow values that are consistently higher than expected by the PCM. The secondary MAF sensor is over-reading airflow, causing the PCM to over-fuel the affected bank. The driver may notice rich-running symptoms on one bank including black exhaust smoke, fuel odor, poor economy, and potentially fouled spark plugs on bank 2.
Common Causes
35%
Faulty MAF 'B' sensor with calibration drift or contamination reading high
25%
Turbulent airflow caused by aftermarket intake or incorrectly installed air filter on bank 2
20%
Restricted exhaust on bank 2 causing backpressure effects on intake metering
10%
Wiring issue causing higher than normal signal voltage on MAF 'B' circuit
10%
PCM calibration issue specific to MAF 'B' sensor scaling
Diagnostic Steps
1
Compare MAF 'A' and MAF 'B' readings at identical engine conditions — if 'B' reads significantly higher than 'A' on a symmetric V-engine, the 'B' sensor is suspect.
2
Check bank 2 long-term fuel trims — a significantly negative LTFT (removing fuel) confirms the MAF is over-reporting airflow.
3
Inspect the bank 2 intake system for aftermarket modifications, improperly seated air filter, or missing components that could create airflow disturbances.
4
Check the bank 2 exhaust backpressure with a gauge installed in the pre-cat O2 sensor bung — should be below 1.5 PSI at idle.
5
Replace the MAF 'B' sensor if cleaning does not resolve the high reading and wiring checks are normal.
Estimated Repair Cost
$30 - $400
Parts + labor, varies by vehicle and location
The mass or volume air flow sensor on circuit 'B' is reporting airflow values that are consistently higher than expected by the PCM. The secondary MAF sensor is over-reading airflow, causing the PCM to over-fuel the affected bank. The driver may notice rich-running symptoms on one bank including bla...
The most common cause of P00BF (Mass or Volume Air Flow "B" Circuit Range/Performance - Air Flow Too High) is: Faulty MAF 'B' sensor with calibration drift or contamination reading high
Typical repair costs for P00BF range from $30 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive but with poor fuel economy and potential secondary damage from rich running. Extended operation can foul spark plugs, contaminate the catalytic converter, and dilute engine oil with unburned fuel. Diagnose within a week to prevent catalytic converter damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P00BF to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel / Air Metering System
Difficulty
Type
Generic (SAE)
Recommended Tools
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