P00B8
MAP - Mass or Volume Air Flow Correlation Bank 2P00B8 is a generic OBD-II powertrain diagnostic trouble code: MAP - Mass or Volume Air Flow Correlation Bank 2. It is logged by the engine control unit when the air/maf monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P00B8 means
DTC P00B8 is stored when the powertrain control module (PCM) detects a significant discrepancy between the signal from the manifold absolute pressure (MAP) sensor and the mass or volume air flow (MAF/VAF) sensor on engine Bank 2 — the cylinder bank that does not contain cylinder number one. Both sensors provide information about the quantity of air entering the engine: the MAF sensor measures actual air mass flow at the intake, while the MAP sensor monitors manifold vacuum to infer engine load. The PCM continuously cross-checks these two signals; under normal operation they track each other within a calibrated tolerance window. When the two signals diverge beyond that threshold — due to a faulty sensor, a vacuum leak, a clogged or contaminated MAF element, or a cracked air intake pipe — the PCM logs P00B8. This correlation error compromises the PCM's ability to accurately calculate fuel injection pulse width and ignition timing for Bank 2, potentially causing a rich or lean condition, rough running, and increased emissions. The code is most relevant to V-configuration and flat/boxer engines equipped with independent air metering for each cylinder bank.
Common causes
Most-frequently reported root causes when P00B8 is logged.
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1
Faulty or contaminated MAF/VAF sensor on Bank 2 providing incorrect mass flow readings
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2
Defective MAP sensor producing inaccurate manifold pressure signals
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3
Vacuum leak downstream of the MAF sensor (cracked intake hose, loose clamp, split intercooler pipe) allowing unmetered air into Bank 2 manifold
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4
Clogged or dirty air filter causing restricted airflow and unbalanced sensor signals
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5
Open or shorted wiring/connector on either the MAP or MAF sensor circuit
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6
Cracked or broken air inlet pipe between the air filter housing and throttle body
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7
PCM failure or programming error causing incorrect correlation threshold calibration
Symptoms drivers notice
How to diagnose P00B8
A typical diagnostic flow when this code is present.
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1
Retrieve all stored DTCs and freeze-frame data; note any accompanying fuel trim, MAF, or MAP codes that may help isolate the faulty component
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2
Inspect the entire air intake system from the air filter to the throttle body on Bank 2 for cracked hoses, loose clamps, or damaged intercooler pipes that could introduce unmetered air
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3
Perform a manual engine vacuum test with a vacuum gauge; insufficient vacuum indicates a mechanical engine issue that must be resolved before further sensor testing
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4
With the engine running, monitor live MAP and MAF data on a scan tool; compare Bank 2 values against expected values at idle and under load — a sensor stuck at an implausible value indicates a faulty component
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5
Using a digital multimeter (DVOM), verify reference voltage (typically 5 V) and a clean ground at both MAP and MAF sensor connectors; check signal voltage at idle and compare to specifications
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6
Disconnect the MAF sensor and clean the sensing element with MAF-specific cleaner if contamination is visible; retest after reassembly
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7
If all sensors and wiring test within specification, check for PCM technical service bulletins (TSBs) before suspecting a PCM fault
Related powertrain codes
- P0068 — MAP/MAF - Throttle Position Correlation
- P006A — MAP - Mass or Volume Air Flow Correlation Bank 1
- P00BC — Mass or Volume Air Flow A Circuit Range/Performance - Air Flow Too Low
- P00BD — Mass or Volume Air Flow A Circuit Range/Performance - Air Flow Too High
- P00BE — Mass or Volume Air Flow B Circuit Range/Performance - Air Flow Too Low
- P00BF — Mass or Volume Air Flow B Circuit Range/Performance - Air Flow Too High
Frequently asked questions
Which sensor is more likely to be faulty — the MAP or the MAF?
In practice, the MAF sensor fails more often due to contamination from oil vapour, dust, or cleaning with improper chemicals. However, vacuum leaks are equally common triggers for this code. Perform a thorough intake leak inspection before replacing either sensor.
Can a dirty air filter cause P00B8?
A severely clogged air filter can restrict airflow enough to create a measurable imbalance between MAP and MAF readings, particularly at higher engine loads. Always check and replace the air filter as part of the initial inspection before condemning more expensive components.
Does P00B8 only affect V-engine or boxer-engine vehicles?
Yes. Bank 2 designations are only relevant on engines with two cylinder banks — typically V6, V8, V10, and horizontally-opposed (boxer) engines. Inline four-cylinder engines have only one bank and would not set a Bank 2 correlation code.
Will cleaning the MAF sensor fix P00B8?
If contamination is the root cause, cleaning the MAF element with a dedicated MAF sensor cleaner spray can restore correct readings. However, if the sensor element is physically damaged or the correlation error is due to a vacuum leak or MAP sensor fault, cleaning alone will not resolve the code.
Disabling P00B8 in software
RaceTune can permanently disable P00B8 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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