P0104 – Meaning, Causes, Symptoms, & Fixes

Code P0104 Definition

Mass Airflow (MAF) Electrical Circuit Erratic and Irregular Output

What Does P0104 Mean?

The Mass Airflow (MAF) sensor measures the amount of air entering the engine. When code P0104 is set, there is a inconsistent or irregular voltage output to the ECM, PCM, or ECU depending on your car type (check your owner’s manual for your specific car).

P0104 Symptoms

  • Check Engine Light
  • Lower fuel economy
  • Black smoke from tailpipe
  • Rough operation

P0104 Causes

  • Inconsistent air flow from the air cleaner sensor
  • Bad wiring electrical connection in to MAF sensor
  • Bad vacuum hose
  • Carbon covered MAF sensor screens
  • Dirty air filter
  • Corroded/Damaged MAF circuit terminals

Code P0104 Severity – Moderate   

The trouble code P0104 will not prevent the vehicle from having any driveability issues (unless the leak is very large) but should be taken care of as soon as possible as the continuation of driving could cause other issues within the vehicle.

Code P0104 Common Diagnosis Mistakes

Replacing the air filter without diagnosing the Mass Air Flow (MAF) sensor and inspecting the circuitry.

P0104 Diagnosis

  • Tools Needed to Diagnose:

Difficulty of Diagnosis and Repair – (1-4)

  1. Visually inspect wiring around Mass Air Flow (MAF) Sensor for any frayed, broken, corroded wires.
  2. Visually inspect the air intake system for any possible leaks present.
  3. Check your air filter and replace if needed.
  4. Clean your MAF sensor to make sure that there are no pieces in the system that do not belong. Check out this video for a visual step by step walk through.
  5. The quickest way to check if your Mass Air Flow (MAF) sensor is the problem is to disconnect your electrical harness while your car is running. Check your owner’s manual to locate the MAF sensor for your specific car.
    1. NOTE: Make sure that all other parts of your vehicle have cooled down (6-8 hours inactive) before doing this test. Reference this video for visual reference
    2. If your car’s engine shuts off, your MAF sensor is operating normally. If it does not shut off it means that your MAF sensor is not operating normally and should be replaced.
  6. If these steps do not clear your Check Engine Light, you may need to visit a mechanic because there may be electrical issues.

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