Manifold Absolute Pressure Sensor
2021 Toyota Camry · 2.5L I4
Sensor Type
piezoresistive
Waveform Type
dc-variable
Location
Mounted on intake manifold upper plenum or connected via vacuum line to manifold, passenger side near throttle body
Pins
3-pin connector
Timebase
100ms/div for general observation, 10ms/div for intake pulse analysis
Voltage Scale
1V/div
Trigger
Not applicable for DC observation
Wiring
5V reference - red or orange, signal output - green or light blue, ground - black or brown
Expected Voltage Range
At Idle
0.9V to 1.8V
At Higher RPM
4.2V to 4.8V
Expected Pattern
Smooth DC voltage reflecting manifold vacuum, idle 1.0-1.5V (high vacuum), rising to 4.5V at WOT (atmospheric pressure), pulses visible at low timebase showing intake pulses
Known-Good Waveform
At idle, voltage should be stable at 1.0-1.5V indicating proper manifold vacuum (17-21 inHg). During snap throttle to WOT, voltage should rise smoothly to 4.5V (near atmospheric pressure). At faster timebase (10ms/div), distinct intake pulses should be visible showing individual cylinder intake strokes. Key-on-engine-off voltage should read approximately 4.5V (barometric pressure reference).
Common Failure Patterns
Voltage stuck at 4.5-4.8V regardless of engine operation, no change with throttle
Cause: Vacuum line disconnected or blocked, failed MAP sensor diaphragm allowing atmospheric pressure reading
Idle voltage higher than 2.0V indicating low vacuum, or excessive fluctuation
Cause: Vacuum leak in intake manifold, failed PCV system, or valve timing issue reducing vacuum
Voltage stuck at 0.5V or below regardless of manifold pressure
Cause: Failed MAP sensor, short to ground in signal wire, or internal sensor failure
Diagnostic Tips
The 2.5L A25A-FKS engine uses MAP sensor primarily for barometric reference and load calculation backup to MAF. Compare KOEO voltage (barometric) to actual barometric pressure - should correlate to local altitude. Check VVT-i system operation if MAP shows low vacuum at idle; cam timing faults reduce manifold vacuum significantly on this engine.
Related Diagnostic Trouble Codes
P0105P0106P0107P0108P0109
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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