P3138 AUDI, VOLKSWAGEN: INTAKE FLAP FOR AIRFLOW CONTROL CONTROL DIFFERENCE
Description of DTC code P3138
Vehicle manufacturers in certain cases employ a variable geometry intake manifold, which allows the airflow in the manifold to be changed for specific conditions. Under low-load situations, a long, thin manifold channel is ideal for flow velocity and swirl or turbulence. But in conditions requiring high load, a short runner is ideal.
Swirl velocity and intake turbulence are necessary to form and agitate the fuel mixture. For this, a position sensor can be attached to the control circuit to monitor the valve for electrical or mechanical failures. Also, the actuator can be tested to check the operation of the circuit, and live data can be used to validate the position feedback.
The P3138 OBDII diagnostic code on Audi and Volkswagen vehicles is set when a difference in airflow control of the intake manifold inlet flap is detected.
DTC P3138 OBD2 is set by one of the following factors:
Intake Manifold Runner Position Sensor wires may have deficiencies causing the malfunction.
The Intake Manifold Runner Position Sensor circuit may be shorted or open due to poor connections.
The Intake Manifold Runner Position Sensor may be defective.
The Intake Manifold Runner Control Solenoid could be in poor condition.
Possible solutions of the DTC code P3138
To troubleshoot the P3138 OBDII fault code you must do the following:
Consult the Technical Service Bulletins.
Inspect the Intake Manifold Runner Position Sensor wiring, connectors, and connections for common deficiencies. Correct as necessary.
Measure the Intake Manifold Runner Position Sensor circuit voltages and check for open or shorted circuits. If you detect one of these conditions, make the appropriate repairs.
Using the manufacturer's diagnostic steps, verify the integrity of the Intake Manifold Runner Position Sensor. If you detect obvious damage to the sensor, consider replacing it.
Check that the resistance of the intake manifold runner control solenoid is within the range specified by the manufacturer. A different resistance indicates damage to the solenoid and should be replaced.