Intake Air Temperature Sensor
2021 Honda Accord · 1.5L I4 Turbo
Sensor Type
thermistor
Waveform Type
dc-variable
Location
Integrated into Mass Air Flow sensor housing on intake air duct between air filter and turbocharger compressor inlet
Pins
2-pin connector
Timebase
2s/div for monitoring intake temperature changes
Voltage Scale
1V/div
Trigger
Not applicable for DC monitoring
Wiring
Blue/Yellow (signal to ECM pin A8) and Green/White (sensor ground, shared with MAF)
Expected Voltage Range
At Idle
1.5V to 3.5V
At Higher RPM
0.8V to 2V
Expected Pattern
DC voltage inversely proportional to temperature, responds slowly to ambient changes but drops under sustained boost
Known-Good Waveform
At ambient temperature (68-77°F) should read 2.0-3.0V. Under boost conditions temperature rises and voltage drops to 1.2-1.8V. During cold starts below 32°F, expect 3.5-4.0V. Signal should be stable with gradual changes only, no rapid fluctuations.
Common Failure Patterns
Reading stuck at -40°F (4.8-5.0V) on scan tool
Cause: Open circuit in IAT sensor element or wiring, poor connection at MAF connector
Reading stuck at very high temperature (0.1-0.3V)
Cause: Shorted sensor element or wire shorted to ground
Related DTCs: P0112
Implausible temperature readings compared to ECT at startup
Cause: Sensor drift due to oil contamination from turbo seal leak or sensor degradation
Related DTCs: P0111
Diagnostic Tips
On this turbocharged engine, monitor for oil contamination on IAT sensor from failed turbo seals - this causes false high temperature readings and rich fuel mixture. ECM compares IAT to ECT at startup; differences greater than 15°F when cold-soaked trigger rationality codes.
Related Diagnostic Trouble Codes
P0110P0111P0112P0113P0114
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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