The manifold absolute pressure (MAP) sensor measures boost in the intake, and a dirty or failed one causes low power, smoke, and boost codes.
What it does
The MAP sensor reports intake manifold pressure so the computer can control fueling and the turbo. On diesels it is central to boost management, and soot or oil can foul it, giving the computer a false reading that hurts performance.
Signs it is failing
- Low power and hesitation
- Excess smoke under load
- Boost or MAP fault codes
- Poor throttle response
Replacement and what to know
A fouled MAP sensor can sometimes be cleaned, but a failed one is replaced. Because a genuine boost problem produces similar symptoms, compare the sensor reading to expected boost and inspect the charge-air plumbing for leaks before deciding.
Frequently asked questions
What does the MAP sensor do?
It measures intake manifold boost pressure so the computer can control fueling and the turbo.
Can soot foul a MAP sensor?
Yes. Soot and oil can coat the sensor and skew its reading, causing low power and boost codes.
Sensor or real boost problem?
Compare the reading to expected boost and check for leaks. An erratic sensor points to the sensor; a consistent shortfall points to a boost issue.
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