Diagnostic Trouble Code P0104

. OP0104 “Mass Air Flow (MAF) A Circuit Intermittent”


What is code P0104?

Code P0104 stands for “Mass Air Flow (MAF) A Circuit Intermittent”. This diagnostic trouble code can happen for a number of reasons related to the mass air flow sensor in your engine compartment. Therefore, it is important to have a qualified technician diagnose the specific problem that caused the code to be stored in your vehicle’s computer.

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.

What does code P0104 mean?

Code P0104 is similar to other codes in this series (such as P0102 or P0103) but this one has to do with the voltage sent to the ECM (engine control module) being intermittent (rather than too low or high). The signal is erratic or inconsistent.

Your engine requires that a specific mixture or ratio of air and fuel enter the combustion chambers in order for combustion to happen as it should. When that ratio is out of balance, with too much air (too “lean”) or too much fuel (too “rich”), vehicle emissions increase and engine performance and fuel economy decrease.

One method that some vehicle manufacturers use to determine how much air is flowing into the engine is to mount a sensor in the air stream as it enters the intake manifold of the engine. Air passes through a filter (the engine air filter), through the mass air flow sensor housing, and finally into the engine.

When your engine is running, the mass air flow sensor constantly relays air flow data to the ECM. The ECM, in turn, uses the data to determine a number of conditions. For instance, it helps to determine how much fuel needs to be injected into the cylinders, when the engine valves should be opened and closed, and when each spark plug should fire. These questions and more are informed, in part, by the mass air flow sensor.

If the ECM detects that the output voltage from the mass air flow sensor is inconsistent, it will store a code P0104 and turn on the check engine light.


What causes code P0104?

A number of causes can trigger a code P0104. That is why an accurate diagnosis is essential. Causes of this code include:

Most likely

  • Inconsistent airflow from the engine air cleaner ($18-$52)
  • Clogged mass air flow sensor 
  • Faulty mass air flow sensor (average cost $238)

Other possibilities

  • Faulty wiring or electrical connection
  • Improper routing of the wires too close to high voltage components
  • Vacuum leak or other leak in the air intake system


What symptoms are associated with this code?

Common signs associated with a code P0104 include the following:


How does a technician diagnose code P0104?

If a diagnostic scan of your vehicle indicates a code P0104, a technician will perform tests to pinpoint the problem. These tests include checking for any related trouble codes. The technician will also use the scan tool to read the live data of the mass air flow sensor across a variety of operating conditions. The mass air flow sensor and engine air cleaner are also checked for signs of obstruction. Or loose hoses that might lead to an air leak. The technician might also perform tests on the sensor itself using a multimeter. This is to verify that sufficient voltage is reaching the device while in operation. If necessary, the technician might perform further inspection of the ECM to verify proper operation.


How serious is this code?

In some cases, a code P0104 might not show up with immediate drivability issues. Driving in the short term might lead to reduced fuel economy or a failed emissions test. Or maybe even a stalled vehicle. But driving long term with this code can cause the engine to run too rich, or, more importantly, too lean, which is a condition that can cause internal engine damage. For these reasons, a vehicle should not be driven for long with a check engine light on without scheduling an appointment for an accurate diagnosis.

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.


Related Diagnostic Trouble Codes

P0100 “Mass Air Flow Sensor A Circuit Problem”

P0101 “Mass Air Flow Operating Range or Performance Problem”

P0102 “Mass Air Flow Sensor A Circuit Low”

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