01 0.008 Seconds: Inside the World's Fastest Gearbox Technolog… • 02 Airbus and Boeing: The Battle of the Titans • 03 Inline vs V Engine: Pros, Cons, Power, and Fuel Efficiency • 04 How to Calibrate Your Car’s Sensors After Repairs (ABS, TPM… • 05 How EVs are Reshaping Auto Repairs and Opening Doors for Me… • 06 Why Your Garage Has Customers But No Profit • 07 How Self-Driving Cars See and Detect Objects • 08 B0017 and B0018 Codes: Right Front or Passenger Frontal Dep… • 09 Can a Fuel Injector Cleaner Damage Your Engine? Here’s What… • 10 Is the Toyota Supra Saying Goodbye? Here's What We Know •

DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P00F6

P00F6Humidity Sensor Circuit Intermittent/Erratic

P00F6 indicates that the powertrain control module (PCM) has detected an intermittent or erratic signal from the humidity sensor circuit, which is used to measure ambient moisture for climate control and engine management strategies. The PCM sets this code when the sensor's voltage or duty cycle jumps unpredictably or drops out momentarily, rather than failing completely.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp).
  • Often no symptoms besides the warning light, especially in dry weather.
  • Inconsistent or poor automatic climate control performance, such as windows fogging unexpectedly.
  • Possible slight decrease in fuel economy if the PCM alters fuel or ignition timing based on faulty humidity data.
  • In rare cases, a rough idle or hesitation when the engine is cold and humid.
  • Intermittent operation of the automatic headlights or wipers if the humidity sensor is integrated with the rain sensor.

Common causes, most likely first

  1. Loose, corroded, or damaged electrical connector at the humidity sensor.
  2. Chafed or broken wires in the sensor circuit, often near the sensor or where the harness flexes.
  3. Water intrusion into the sensor housing or connector, causing intermittent shorts.
  4. Failing humidity sensor that produces erratic signals under certain temperature or moisture conditions.
  5. Poor ground connection for the sensor circuit, leading to voltage fluctuations.
  6. PCM software glitch or internal fault in the sensor input circuit (less common).

How to diagnose and fix it

  1. Inspect the humidity sensor connector and wiring for corrosion, moisture, or physical damage; clean and dry as needed.
  2. Perform a wiggle test on the sensor harness while monitoring live data to reproduce the intermittent signal.
  3. Check the sensor's ground circuit for excessive resistance and repair any poor connections.
  4. Measure the sensor signal voltage or duty cycle with a multimeter or oscilloscope and compare to manufacturer specifications.
  5. Replace the humidity sensor if it fails bench or live-data testing.
  6. Clear the diagnostic trouble codes (DTCs) and verify the repair by driving the vehicle under varying humidity conditions.
  7. If the code persists, inspect the PCM connector and wiring for intermittent faults, and reflash or replace the PCM only as a last resort.

Intermittent Humidity Sensor Traps to Avoid

  • A common oversight is replacing the humidity sensor without first checking the connector for water intrusion, which often causes intermittent signals that mimic a failed sensor.
  • The humidity sensor shares wiring with the rain sensor on some vehicles, so a fault in the rain sensor circuit can set P00F6 even when the humidity sensor itself is fine.
  • Technicians sometimes misdiagnose P00F6 as a climate control problem and overlook that the PCM uses humidity data for fuel injection and ignition timing, leading to driveability complaints.
  • In dry climates, the code may only appear during rare humid mornings, so a road test under controlled conditions with a scan tool recording live data is essential.
  • A weak battery or charging system can cause voltage spikes that disrupt sensor signals, so always verify battery health before condemning the sensor.

Can I keep driving with P00F6?

The vehicle remains safe to drive because the fault is intermittent and does not affect core engine operation, but avoid long trips in heavy rain or high humidity until repaired, as climate control performance may degrade.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage