P0068: MAP/MAF – Throttle Position Correlation
The airflow or manifold pressure reading does not match the throttle opening.
Normal risk
Usually drivable, but the engine may limit power. Have it checked soon.
Short answer · Can I keep driving with P0068?
Usually yes, with care. Many engines go into reduced-power mode with this code. Have it checked soon.
What does P0068 mean?
P0068 means the engine control unit compares the measured air, from the MAF or MAP sensor, with the air it expects from the throttle position and engine speed, and the two do not agree. An intake leak after the throttle, a dirty or failed air-flow sensor, a dirty throttle body or a throttle position sensor fault are typical causes.
What the car does when the code is set
The check engine light comes on. The engine uses a substitute value, so it may hesitate, idle unevenly, use more fuel or produce black smoke. On turbo engines, power may be limited.
How the system works
The manifold absolute pressure (MAP) sensor measures the pressure, or vacuum, in the intake manifold. Low pressure means low engine load; high pressure means high load or boost. The engine control unit uses it to calculate load and fuel quantity, and on turbo engines to control boost. The sensor sends a voltage that rises with pressure; with the engine off, the reading should match outside air pressure.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Split or disconnected vacuum hoseThe sensor reads manifold pressure through a small hose or port; a leak or loose hose gives a wrong reading.
- Intake leakAir leaking past a gasket or hose changes manifold pressure and the fuel calculation.
- Dirty or oily sensorOil vapour from the crankcase ventilation can coat the sensing element.
- Wiring or connector faultA broken wire, corrosion or a poor reference voltage changes the signal.
- Failed sensorThe sensor itself can drift or fail with age.
How it is diagnosed
- Check the hose and connectorMake sure the sensor is firmly connected and any vacuum hose to it is intact and not blocked.
- Compare the reading with the engine offWith the ignition on and the engine stopped, manifold pressure should be close to the barometric pressure for your altitude.
- Look for intake leaksA smoke test finds leaks in the intake manifold, hoses and gaskets.
- Measure supply, ground and signalA workshop checks the reference voltage and signal at the connector against the service data.Do not pierce wire insulation to take readings; it lets moisture in and causes new faults.
Questions about P0068
Which part is wrong with P0068?
The code only says the readings disagree. Live data helps: compare airflow, manifold pressure and throttle angle at idle and when revving. A leak shows as too much air for the throttle opening.
Is the MAP sensor the same as the MAF sensor?
No. The MAP sensor measures pressure in the intake manifold, the MAF sensor measures the air flow entering the engine. Some engines use both.