Manifold Absolute Pressure (MAP) / Barometric Pressure Circuit Malfunction
What does P0105 mean?
The P0105 code means the vehicle's onboard diagnostic system has detected: Manifold Absolute Pressure (MAP) / Barometric Pressure Circuit Malfunction. This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Rough idle and engine surging
- Poor acceleration and reduced power
- Black smoke from exhaust (running rich)
- Engine may stall or hesitate
Probable Causes (Ranked by Likelihood)
- Failed MAP sensor Very High
- Cracked or disconnected vacuum hose to MAP sensor High
- Wiring issue -- open, short, or damaged connector Moderate
- Vacuum leak at intake manifold Moderate
- PCM internal fault Low
Step-by-Step Diagnostic Procedure
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With key on engine off, check MAP sensor voltage on a scan tool. It should read approximately 4.5V (atmospheric pressure). At idle, it should drop to 1.0-2.0V (manifold vacuum).
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Inspect the vacuum hose from the intake manifold to the MAP sensor for cracks, kinks, or disconnection. Replace if damaged.
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Disconnect the MAP sensor and measure the reference voltage (should be 5.0V) and ground (near 0 ohms) at the connector.
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With the engine off, apply vacuum to the MAP sensor using a hand vacuum pump. The voltage should drop smoothly as vacuum increases.
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Check for intake manifold vacuum leaks using a smoke machine or carb cleaner spray. Leaks will cause incorrect MAP readings.
Frequently Asked Questions
Can I drive with code P0105?
You can drive short distances, but the engine may run rough, lack power, or stall. The PCM relies on the MAP sensor for fuel and ignition timing calculations, so a malfunction affects overall engine performance.
What does the MAP sensor do?
The MAP sensor measures the pressure inside the intake manifold. The PCM uses this information to calculate engine load, adjust fuel injection timing, and control ignition timing. It is critical for proper air-fuel ratio management.
Can a vacuum leak cause P0105?
Yes. A vacuum leak between the intake manifold and the MAP sensor will cause incorrect pressure readings. This includes a cracked vacuum hose to the sensor, a leaking intake gasket, or a broken vacuum fitting.