P0103 Trouble code definition
Mass Airflow (MAF) Circuit High Air Flow and High Voltage Output
- The Code P0103 code is often associated with a P0100, P0101, P0102 and P0104 codes which are closely related.
What the P0103 code means
P0103 is the code for a problem with the Mass Airflow (MAF) Sensor having a high voltage output to the Engine Control Unit (ECU).
What causes the P0103 code?
The MAF Sensor high voltage output to the ECU may have several causes:
The source of the problem is the sensor voltage output is higher than normal or required by the ECU to function with other sensor signals.
The wiring or MAF sensor may be too close to higher voltage consumption components, alternators, ignition wires, etc. causing inaccurate output signals.
The air intake system from the air filter assembly may have a large leak like a bad vacuum hose, air intake hose, loose hose clamps or other intake leak before the MAF sensor.
MAF sensors must operate within specific ranges to send correct signals for the ECU to adjust correctly and in conjunction with other sensors for proper engine operation.
What are the symptoms of the P0103 code?
P0103 code will be normally preceded by the Check Engine Light coming on the dashboard display.
Generally, the vehicle runs well enough to drive. The engine often operates near normally but it may run slightly erratically, have less power, back fire and idle inconsistently higher than normal.
If the engine runs poorly, the situation requires attention as soon as possible or internal engine damage could occur.
How does a mechanic diagnose the P0103 code?
P0103 is diagnosed with a test with an OBD- II scanner. The OBD-II code should be reset and then road test the vehicle to see if the Check Engine Light and code comes back. He can observe this by watching it live on his scanner while driving. If the code comes back, then the mechanic will need to do a close visual inspection to determine if any electrical connector, wiring, sensor, air cleaner, intake or vacuum hoses, loose hose clamps, and MAF need repair or replacement.
If no problems are noted, then the next step is to have the mechanic do a circuit test with a multimeter that has a digital display to show sampling rate and sensor range readings to determine if the MAF sensor output is really too high.
Common mistakes when diagnosing the P0103 code
Diagnostic errors are largely due to not following the proper procedure:
First, follow the test procedure for inspecting the connector, wiring and sensor. Do not buy a MAF sensor unless the other tests indicate no problem.
Before buying a MAF sensor, try cleaning it with a specialized spray cleaner made for MAF sensors such as CRC 05110 as these often get considerable carbon build up from the emission system, especially at idle.
The air intake system may have very simple causes like loose clamps, air hoses or vacuum lines, so a close inspection is necessary before buying an expensive MAF unit.
How serious is the P0103 code?
The P0103 code generally will not prevent the car from driving unless the leak is massive.
Take the car to a qualified technician check it out as soon as possible.
The MAF sensor issue can cause excessive fuel consumption, smoking, rough operation and difficulty starting in certain circumstances. Continued driving could cause internal engine damage.
Often times, if the Check Engine Light came on immediately at start up, the OBD- II system can be reset and the vehicle will operate normally.
What repairs can fix the P0103 code?
The most common potential repairs for the P0103 code are as follows:
Recheck code with a scanner. Reset the fault codes and perform a road test.
If the P0103 code comes back, then follow the order of the test procedure.
Inspect the electrical connector to ensure it is attached correctly. Disconnect it and then reinstall to ensure fresh and positive electrical connection.
Carefully inspect for wiring being frayed, damaged or broken on the connector. Repair or replace as necessary before further testing.
Check for vacuum leaks, loose hoses, bad fittings, and clamps on the intake, especially on older cars. Old components can get hard and crack.
Additional comments for consideration regarding the P0103 code
Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start up or prolonged stress situations on the drive train.
If the Check Engine Light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset using the scanner and the problem may not reoccur. This is why it is important to verify the fault and reset it before doing any repairs.
Need help with a P0103 code?
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This article originally appeared on YourMechanic.com as P0103 OBD-II Trouble Code: Mass Airflow (MAF) Circuit High Air Flow and High Voltage Output and was authored by John Nelson.