Fuel and air

P00F3 — Humidity Sensor Circuit Range/Performance

Severity: low Safe to drive

What P00F3 means

The engine control module (ECM) is receiving a signal from the intake air humidity sensor that is outside the expected range or does not agree with other data such as air temperature, load or airflow. Humidity is used to fine-tune air/fuel metering, ignition timing and emissions control. On many vehicles the sensing element is built into the mass airflow (MAF) sensor or an intake pressure/temperature sensor.

Symptoms

  • Check Engine light on
  • Rough idle
  • Hesitation when accelerating
  • Slightly reduced power
  • Higher fuel consumption
  • Unrealistic humidity readings on a scan tool

Possible causes

  1. Failed humidity sensor or sensing element (often part of the MAF sensor)
  2. Sensor contaminated by moisture, oil or dirt
  3. Damaged wiring, open or short in the sensor circuit
  4. Corroded or loose connector terminals
  5. Extreme weather (very cold or very humid) causing a false trigger
  6. ECM software or calibration issue (uncommon)

How to diagnose

  1. Read all codes and freeze frame data, and look for related MAF, intake air temperature or manifold pressure codes
  2. Clear the code and see if it returns, noting the weather and conditions when it sets
  3. Inspect the sensor and connector for moisture, oil, corrosion or a loose latch
  4. Check the harness for chafing, breaks and shorts to ground or power
  5. Compare the scan tool humidity and air temperature readings with actual conditions and with other sensors
  6. Measure power, ground and reference voltage at the sensor connector using the factory wiring diagram
  7. Look for technical service bulletins or ECM software updates for your vehicle

Common fixes

  • Clean the connector and restore solid terminal contact
  • Repair or replace damaged wiring or the connector
  • Replace the humidity sensor or the MAF sensor assembly if it is faulty
  • Update the ECM software if the manufacturer recommends it

Questions and answers

Can I drive with a P00F3 code?

Usually yes, as the code does not normally threaten the engine. You may notice rough running or worse fuel economy, so have it checked in the near future.

Where is the intake humidity sensor located?

It is most often built into the MAF sensor or mounted in the intake tract after the air filter. The exact location depends on the vehicle.

Can weather cause P00F3?

Yes, very humid conditions or sharp temperature swings can sometimes give false readings. If the code does not return after clearing it, weather may be the cause, but still inspect the sensor and connector.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.