Unmetered air leak on the bank 2 side of the intake, such as a split intake hose, loose clamp or leaking manifold gasket; Faulty or contaminated mass air flow sensor serving bank 2; Faulty MAP sensor, or a blocked or leaking sensor port or vacuum line; Damaged wiring, poor connector contact or a high resistance earth or supply on the MAP or air flow sensor circuit; Restricted air filter or intake ducting on the bank 2 side; Boost leak or charge air pipe fault on turbocharged engines; Exhaust restriction or an intake or exhaust valve timing fault that changes the airflow to pressure relationship.

P00B8

MAP - Mass or Volume Air Flow Correlation Bank 2.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
0: AreaFuel and air metering, auxiliary emission controls
B8: FaultThe specific fault in that area

What it means

P00B8 means the engine control unit has found that the manifold absolute pressure (MAP) signal and the mass or volume air flow signal for bank 2 do not agree with each other. The ECU expects a certain pressure for a given amount of airflow at the current load and throttle position. It set the code because the two readings differed by more than the allowed amount. Bank 2 is the side without cylinder 1, and how the sensors are arranged for it depends on the engine.

Symptoms

Engine warning light on
Poor or hesitant acceleration
Rough or unstable idle
Poor fuel economy
Possible limp mode or reduced power
Other fuel trim or lean/rich codes stored alongside

Possible causes

Unmetered air leak on the bank 2 side of the intake, such as a split intake hose, loose clamp or leaking manifold gasketlikely
Faulty or contaminated mass air flow sensor serving bank 2likely
Faulty MAP sensor, or a blocked or leaking sensor port or vacuum linepossible
Damaged wiring, poor connector contact or a high resistance earth or supply on the MAP or air flow sensor circuitpossible
Restricted air filter or intake ducting on the bank 2 sidepossible
Boost leak or charge air pipe fault on turbocharged enginespossible
Exhaust restriction or an intake or exhaust valve timing fault that changes the airflow to pressure relationshiprare

How to diagnose

Read all stored and pending codes and note the freeze frame data (load, engine speed, throttle position, temperature) to see when the fault set.
Check live data for MAP, air flow and fuel trims on both banks at idle and under load, and compare bank 2 with bank 1 where fitted.
Visually inspect the air filter, intake ducting, clamps, breather hoses and vacuum lines on the bank 2 side for splits, looseness or oil contamination.
Inspect the connectors and wiring to the MAP and air flow sensors for corrosion, damage, bent pins and chafing.
Check the sensor supply voltage, earth and signal voltage against the manufacturer's specification.
Smoke test the intake system, and on turbocharged engines pressure test the charge air system, to find leaks.
With the engine off and ignition on, compare the MAP reading with barometric pressure, then check it against a known good reference.
If the fault persists, check for exhaust restriction and valve timing issues, following the procedure for that engine.

How to fix

Repair or replace leaking intake hoses, clamps, gaskets or vacuum lines.
Clean or replace the faulty air flow sensor, following the manufacturer's guidance.
Replace the MAP sensor or clear its blocked port or line if it is found faulty.
Repair damaged wiring or connectors and restore proper supply and earth.
Replace a clogged air filter or fix any intake restriction.
Install an updated ECU calibration only where the manufacturer lists one for this fault.

Can I keep driving?

Medium severity

Short, gentle journeys are usually possible, but get it checked soon because the fault can cause poor running, high fuel use and possible limp mode. Avoid heavy loads and hard acceleration until it is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.