Error Code P0103: Mass Air Flow (MAF) Circuit High Input

Error Code P0103 is defined as MAF (Mass Air Flow) sensor or VAF (Volume Air Flow) sensor high input. Basically, this means there’s a problem with the MAF sensor circuit, as it receives a voltage (air flow) significantly higher than expected.

This error code is often associated with P0100, P0101, P0102 and P0104.

Definition

The purpose of the MAF sensor is to ensure the correct amount of air enters the engine, as the ECM (Engine Control Module) uses this information to control the amount of fuel and ignition timing.

Error Code P0103 means the MAF has a higher voltage output to the ECU (Engine Control Unit, an electronic control unit that controls the actuators of the internal combustion engine, ensuring optimal engine performance). Therefore, it is set when the PCM detects the MAF sensor experiencing high voltage output.

Common Symptoms

The most common tell-tale symptom of this code is the illumination of the Check Engine light in the dashboard. Aside from that, there are no noticeable symptoms for this code, making it quite tricky. In some cases, however, it causes poor fuel mileage and a general decrease in power.

Possible Causes

Error Code P0103 is usually caused by a wiring short to positive, or trouble in MAFNAF sensor. Other possible causes include:

  • Damaged wiring or unplugged MAF sensor
  • Corroded or loose electrical terminals in the MAF sensor circuit
  • Faulty MAF sensor

This common code is quite rare, and unlike related Error Code P0102, it doesn’t indicate a dirty MAF. Also, it’s unlikely caused by a problem in the PCM. As you can see above, the common causes are wiring related or interference in the power source.

How to Check

As with most error codes, diagnosis for P0103 starts with resetting the code and then take the vehicle for a test drive to see if it comes back again. If the code comes back, then you should proceed to a close visual inspection. Qualified mechanics look for any damages in the electrical connector, sensor, wiring, air cleaner, loose hose clamps, intake or vacuum hoses, and repair or replace the MAF.

If there are no visible problems, then the mechanic will conduct a circuit test using a multimeter with a digital display to get the sampling rate and sensor range readings to determine whether the output of the MAF sensor is too high.

How to Fix

As with most error codes, the easiest fix for P0103 is to reset the code and check if it comes back through a road test.

  1. After that, proceed to checking all the electrical connectors and make sure they’re attached correctly. Then, disconnect them and plug them again to refresh the positive electrical connection.
  2. Then, look for any signs of damaged, broken or frayed wirings on the connector. Repair or replace as needed before conducting further testing. Make sure the MAF sensor wiring is properly connected, and there are no frayed or broken wires.
  3. Then, check for signs of vacuum leaks, bad fittings, loose hoses, and clamps on the intake, especially on older vehicles. Older vehicles with old components can often be cracked. Look for signs of air leaks near MAF sensor.
  4. You can also pull out the MAF, clean it thoroughly using a spray cleaner like electrical contact cleaner or brake cleaner. Make sure you’re gentle with the sensor.
  5. Check the MAF sensor’s voltage. Make sure you refer with the repair manual of the vehicle for specific instructions and information on this one.
  6. Replace the MAF sensor when needed.

There are times when the Check Engine light comes on and the vehicle seems to run normally. A simple reset of the OBD-II system using the scanner may solve the problem. This is why it’s very important to verify the fault and reset it before doing any repairs.

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