Manifold Absolute Pressure/Barometric Pressure Sensor Circuit Range/Performance

What it means

The manifold absolute pressure (MAP) sensor is sending a signal that is electrically valid but does not make sense compared with other sensors. The manifold absolute pressure (MAP) sensor measures vacuum (pressure) inside the intake manifold so the ECU can calculate engine load and fuel delivery. This usually points to a sensor that is reading wrong, or to a real mechanical problem it is reporting correctly, rather than a broken wire.

Symptoms

• Check engine light on
• Rough idle
• Hesitation and poor power
• Poor fuel economy
• Black smoke from the exhaust
• Hard starting

Probable causes

Most likely first

1. 1Cracked, disconnected or blocked vacuum hose to the sensor
2. 2Vacuum leak in the intake manifold
3. 3Mechanical engine problem causing low vacuum (valve timing, burnt valve)
4. 4Failing sensor giving an inaccurate reading
5. 5Poor connection at the sensor connector

How to diagnose it

Work through these in order before buying parts

1. 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
2. 2Inspect the manifold absolute pressure (MAP) sensor connector and wiring (on the intake manifold or connected to it by a vacuum hose). Look for corrosion, bent or pushed-back pins, oil contamination and chafed insulation.
3. 3Watch the manifold absolute pressure (MAP) sensor reading on live data. With key on and engine off it should read close to barometric pressure (about 100 kPa at sea level). At warm idle a healthy engine usually reads 25–40 kPa (high vacuum).
4. 4Compare the manifold absolute pressure (MAP) sensor reading against related sensors and the real-world condition. If they disagree, find out which one is telling the truth before buying parts.
5. 5If the wiring checks out, test the sensor itself against the specification in a service manual.
6. 6Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.

Common fixes

• Fix the underlying problem the sensor is reporting, if real
• Replace the manifold absolute pressure (MAP) sensor if it reads wrong against a known-good reference