Air Temperature - Actron CP9087 Service Manual

Typical Air Temperature Sensor
What is It?
How is It
Used?
Location
When to Test
What to
Inspect

Air TEMPERATURE

SENSOR
RESISTANCE
The air temperature sensor is a thermistor - a
resister whose resistance changes with temperature.
The hotter the sensor gets, the lower the resistance
becomes. The thermistor is mounted inside the tip of
a threaded metal housing. This is a 2-wire sensor.
The computer needs to know air temperature to
calculate the amount of air entering the engine.
Then, the computer can provide the proper air/fuel
mixture for the desired operating condition.
The sensor is threaded into the intake manifold,
throttle body, rear of air cleaner assembly or
elsewhere along the path of air entering the
engine. Sometimes this sensor is built into a vane
airflow meter or mass airflow sensor assembly.
One connector handles both the air flow and
temperature sensor circuits.
• Related trouble codes sent by computer.
• Driveability problems such as hard starting,
rough idle, stalling, hesitation, stumble, surging,
poor fuel economy, or black exhaust smoke.
Sensor operation (see test on page 2-4). Poor
connections at sensor or computer. Faulty sensor
wiring (open or short circuits). Heavy deposits on
sensor tip which can cause poor response.
Restricted or blocked air passageways.
Engine running too hot (problems with
antifreeze, thermostat, water pump, fan, belts,
low engine oil).
HIGH
LOW
Cold
TEMPERATURE
Hot
2-3