Powertrain, generic · Fuel and air metering, auxiliary emission controls
P00F4 Humidity Sensor Circuit Low
Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo
The humidity sensor measures the relative humidity of the intake air; on documented vehicles it is built into the mass air flow sensor or a combined sensor. The engine control module uses the value, for example, to correct torque and in emission models. One documented design is capacitive and reports humidity as a pulsed signal with a duty cycle that the control module converts back. P00F4 means the signal is below its valid range (for example a duty cycle near zero), typically because the signal wire is shorted to ground or the sensor supply is missing.
Likely causes
Signal wire shorted to ground
Sensor or combined air flow sensor faulty
Sensor supply missing
Symptoms
- Check engine light on
- Usually no noticeable symptoms
- Slightly uneven torque or higher consumption possible
Repair estimate
DifficultyEasyDIY possible
Parts and labour€80–450
Time0.3–1 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
humidity sensormass air flow sensorhumidity sensor wiring
Related codes
References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.