P0104 – Meaning, Causes, Symptoms, & Fixes

Code P0104 Definition

Mass Air Flow (MAF) Electrical Circuit Erratic and Irregular Output

What Does P0104 Mean?

The Mass Air Flow (MAF) sensor measures the amount of air entering the engine. When code P0104 is set, there is an 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). Due to the inconsistent and irregular nature of this code diagnosis can be difficult.

What Are the Symptoms of Code P0104?

  • Check Engine Light
  • Lower fuel economy
  • Black smoke from the tailpipe
  • Rough operation
  • Stalling
  • Hard Start

What Is the Cause of Code P0104?

  • Dirty or damaged air filter (common cause)
  • Leaking vacuum hoses or intake gaskets
  • Debris covering MAF sensing element (common cause)
  • Faulty MAF
  • Faulty electrical connection to MAF sensor
  • Corroded/Damaged MAF circuit terminals

What Is the Severity of Code P0104? – Moderate  

The trouble code P0104 can cause the vehicle to have driveability issues and 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 Mass Air Flow (MAF) before checking for a faulty air filter or debris on MAF sensing element.

Tools Needed to Diagnose Code P0104:

    • FIXD
    • Spray bottle of water
    • Basic hand tools

How to Diagnose Code P0104:

Difficulty of Diagnosis: 3 out of 5

  1. Visually inspect wiring around Mass Air Flow (MAF) Sensor for any frayed, broken, corroded wires.
  2. Conduct a visual and audible inspection of the vacuum lines, and any intake connections to make sure there are no signs of disconnection or outside air leaks. (This includes the intake pipe between the throttle body and MAF)
  3. Listen for a hissing sound which can be a sign of a vacuum leak
  4. Spray water over intake area and listen for idle rpm stumble. If it goes down there is an intake leak. Concentrate the stream on different hoses and gaskets until you find your leak.
  5. Check your air filter and replace if needed.
  6. 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.
  7. 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.
  • 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. (doing this test will cause other MAF codes to populate. After this test clear these codes)
  • 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.
  • If these steps do not clear your Check Engine Light, replace the MAF and retest.

Estimated Cost of Repair

For error code P0104, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair.

  • Mass Air Flow (MAF) $300-$400
  • Vacuum leak $100-$200
  • Wiring repair $100-$200
  • Air Filter $20
  • MAF Cleaning $100-$200 

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