P0103

Circuit Descriptio
The Mass Air Flow (MAF) sensor measures the amount of air which passes through it in a given amount of time. The Powertrain Control Module (PCM) uses this information to determine the operating requirements of the engine in order to control fuel delivery. The PCM calculates the engines fuel requirements by monitoring the current flow on the signal wire from the mass air tow (MAF) sensor. When the volume of air entering the MAF sensor increases, the current flow seen by the PCM from the MAF sensor also increases. When the air flow decreases, the current seen by the PCM also decreases. The MAF sensor is located between the air intake tube and the air cleaner in the RH front area of the engine compartment.

Conditions for Running the DTC
The ignition is ON or the engine is running.

Conditions for Setting the DTC
^ MAF sensor output current is more than 4.9 mA.
^ Condition is present for longer than 5 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.
^ The PCM enters the Fail-Safe Function and determines injector drive time and IAC duty cycle according to the TP sensor and engine speed. EGR valve operation is stopped.

Conditions for Clearing the MIL/DTC
^ The MIL turns off after three consecutively passing cycles without a fault present.
^ A History DTC will clear after 40 consecutive warm-up cycles without a fault.
^ Perform the scan tool clear DTC Information function in order to clear the DTC.

Diagnostic Aids
Check for any of the following conditions:
^ MAF sensor readings vary with the air temperature and barometric pressure. The specifications indicated are at 20°C (68°F) and at sea level.
^ A misrouted wiring harness - Inspect the MAF sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads.
^ A damaged wiring harness - Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving connectors and wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the fault.
^ Check for a restriction. A plugged intake air duct or a dirty air filter element. An acceleration from a stop should cause the MAF displayed on the scan tool to increase from about 2.0 to 3.5 g/sec at idle to 5 to 9 g/sec at 2,500 RPM.

If a DTC P0103 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool clear DTC information function. Road test the vehicle while monitoring the DTC P0103 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0103 appears in the Not Ran Since Code Cleared list, the P0103 diagnostic has not yet run. When the DTC P0103 does not appear in the Not Ran Since Code Cleared list, the P0103 diagnostic has run. If the MIL is NOT ILLUMINATED, and there is no PENDING DTC Status in DTC Information, the P0103 diagnostic has passed. DTCs MUST BE CLEARED in order to view the CURRENT STATUS of the Not Ran Since Code Cleared list. DO NOT FORGET that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for CURRENT or PENDING status, in order to determine the outcome of the diagnostic test involved.

An intermittent malfunction may be caused by a fault in the MAF sensor circuit. Inspect the wiring harness and components for any of the following conditions:
^ Backed out terminals
^ Improper mating of terminals
^ Broken electrical connector locks
^ Improperly formed or damaged terminals
^ Faulty terminal to wire connections
^ Physical damage to the wiring harness
^ A broken wire inside the insulation
^ Corrosion of electrical connections, splices, or terminals

If the DTC P0103 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

Test Description
The numbers below refer to the step numbers in the diagnostic table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2. This step will determine if the fault is present.
3. Review Freeze Frame data to determine when the DTC set. Always record this information.
5. Normal voltage at idle for the MAF sensor signal circuit should be 1.6 volts to 2.0 volts. This voltage reading should increase steadily to 5 volts when engine speed is increased to approximately 4,000 RPM.