Technical Description of OBD-II Trouble Code
The system for controlling the intake air flow in diesel engines detects a high air flow.
What does that mean?
This diagnostic trouble code (DTC) is a generic code that can apply to all diesel engines equipped with OBD-II. However, it is more commonly found in certain Chevy, Dodge, Ford, and GMC trucks.
Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
The Diesel Intake Air Flow Control System (DIAFCS) is typically located on the intake manifold in the intake air stream. This system controls the amount of incoming airflow by adjusting a motor operated by the Powertrain Control Module (PCM). The motor opens and closes a throttle plate to regulate the airflow.
The PCM determines the amount of clean, filtered air entering the engine based on the Diesel Intake Airflow Position Sensor, also known as a MAF sensor. When the air flow control system is activated, the PCM should detect a change in airflow. If there is no change, it indicates a problem with the DIAFCS system or the MAF sensor. These trouble codes are set when the input does not match the normal engine operating conditions stored in the PCM’s memory, even for a brief moment.
The code P02EC is set when there is a detected high air flow condition in the diesel intake air flow control system. This could be due to mechanical issues, such as physical damage to the control system causing an electrical fault, or electrical issues with the DIAFCS motor circuit. These possibilities should not be overlooked during troubleshooting, especially when dealing with an intermittent problem.
The severity of this DTC is generally not severe. If the cause is mechanical, the typical symptom is low idle speed. If it is an electrical failure, the PCM can compensate adequately.
What are some of the symptoms of the code?
Symptoms of a P02EC trouble code may include:
What are some of the common causes of the code?
Possible causes for this P02EC code may include:
What are some P02EC troubleshooting steps?
A good starting point is to check for technical service bulletins (TSB) for your vehicle. There may be a known issue with a known fix provided by the manufacturer, which can save time and money during diagnosis.
Next, locate the DIAFCS motor/control system on your vehicle. It is usually attached to the intake manifold in the intake air stream. Inspect the connector and wiring for any signs of damage, such as scraping, rubbing, bare wires, burn spots, or melted plastic. Separate the connector and inspect the terminals inside for signs of burning or corrosion. Clean the terminals if necessary using electrical contact cleaner and a plastic bristle brush. Apply electrical grease to the terminals before reconnecting.
If a mechanical code was set, use intake cleaner and a clean rag to remove carbon deposits behind the throttle plate of the motor control system. Avoid spraying the cleaner into the engine, as it can cause poor running, misfires, and potential damage to the catalytic converter and engine.
If you have a scan tool, clear the diagnostic trouble codes from memory and check if the P02EC code returns. If it does not, the issue was likely related to the connections.
If the P02EC code does return, further testing of the DIAFCS and its associated circuits is necessary. With the Key Off, disconnect the electrical connector at the DIAFCS motor/control. Use a Digital Voltmeter to check the voltage between the ground terminal and the motor terminal at the DIAFCS sensor wiring harness connector. The voltmeter should read 12 volts according to the manufacturer’s specifications. If not, repair the power or ground wire, or replace the PCM. Refer to the manufacturer’s specifications for complete test procedures specific to your vehicle if unsure.
If the previous test passed and the P02EC code continues to appear, it is likely a failed DIAFCS motor/control. However, a failed PCM cannot be ruled out until the DIAFCS motor/control has been replaced. If unsure, seek assistance from a trained automotive diagnostician. PCMs must be programmed or calibrated to the vehicle for correct installation.
