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P1104 OBD-II Trouble Code: Mass Airflow Sensor Ground Malfunction

diagnostic check engine light

P1104 code definition

A vehicle Powertrain Control Module (PCM) can store a P1104 trouble code when the system encounters an erratic voltage signal from the Mass Air Flow (MAF) circuit. In addition to a P1104 trouble code, other codes that are commonly stored in conjunction with the code include a P1100, P1101, P1102, and P1103 code.

What the P1104 code means

A P1104 trouble code means that the MAF sensor is sending an erratic voltage to the PCM. This erratic behavior results in the storage of a P1104 trouble and the illumination of the check engine light.

What causes the P1104 code?

The causes of a P1104 trouble code can range from a bad MAF sensor, a short within the MAF sensor wiring harness, or simply a loose connection at the MAF sensor. Some other causes of this problem include a dirty or clogged air filter that reduces flow of air to the MAF sensor, the vane of the MAF contaminated with debris, a leak in the vehicle's vacuum system either before or after the MAF sensor, and a faulty PCM.

What are the symptoms of the P1104 code?

Some common symptoms of a P1104 trouble code includes erratic operation by the engine, a high idle, backfiring by the engine, and reduced engine power when accelerating. The conditions that lead to the storage of this code can also cause internal engine damage if left untreated.

How does a mechanic diagnose the P1104 code?

When diagnosing a P1104 trouble code, a mechanic needs an OBD-II code scanner, a digital volt/ohm meter, and an evaporative smoke tester. The mechanic must also take the following steps:

  • Examine the wiring, connectors, and components of the MAF sensor wiring harness, paying particular attention to any damaged or faulty wiring, connectors, or components. In addition, the mechanic should look for any loose wiring or connectors.
  • Inspect the air filter to see if it needs replacing. While the air filter is removed, the mechanic should inspect and clean the MAF sensor.
  • The mechanic should also clean the MAF sensor vane of any debris or moisture.
  • Next, the mechanic should clear the code and test the system to see if it returns.
  • If the code returns, download any stored codes and the freeze frame data from the PCM to help in further vehicle diagnosis.
  • Perform a smoke test using an evaporative smoke tester, looking for leaks around the MAF sensor.
  • Clear the code once again and retest the system to see if it returns.
  • If the code returns, the mechanic should use a digital volt/ohm meter to test the voltage and ground signal of the MAF sensor.
  • On a failure to find a ground signal or voltage from the MAF sensor, the mechanic should disconnect the PCM and other related modules and test the continuity of the sensor with the battery ground.
  • If the MAF sensor tests as good, test the continuity between the PCM and MAF sensor.
  • Clear the code after making the necessary repairs and retest the system to see if it returns again.

Common mistakes when diagnosing the P1104 code

Mechanics treating a P1104 trouble code commonly make the mistake of replacing the MAF sensor without checking the wiring for fault, damage, or looseness beforehand, which turns out to be the problem. The result is that the repair does not fix the problem and the code returns upon clearing. In addition, mechanics should replace a dirty air filter and clean the MAF sensor before attempting part replacement.

How serious is the P1104 code?

While the problems associated with a P1104 trouble code usually do not prevent the vehicle from operating, the resulting reduction in vehicle performance can lead to difficulty when operating the vehicle. In addition, the possible damage to internal engine components means you should have this trouble code diagnosed and fixed as soon as possible.

What repairs can fix the P1104 code?

To successfully repair a P1104 trouble code, the mechanic should perform the following:

  • Replace any faulty or damaged, wiring, connectors, or components in the MAF sensor wiring harness. The mechanic should also make sure all connections are tight before proceeding.
  • Replace the air filter if it is dirty.
  • Clean the MAF sensor with a CRC 05110 spray cleaner. The mechanic needs to allow the sensor to dry completely before replacing. In addition, the mechanic should take care when removing the sensor, so as to not damage the wiring.
  • Repair any leaks detected by the smoke test in the vacuum system.
  • Replace the MAF sensor if it ultimately proves to be bad.
  • Replace the PCM if the problem lies there. The mechanic also needs to program any new PCM they install.

Need help with a P1104 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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