P02E4 Diesel Intake Air Flow Control Stuck Open
OBD-II Trouble Code Technical Description
Diesel Intake Air Flow Control Stuck Open
What does that mean?
This generic powertrain/engine diagnostic trouble code (DTC) can typically apply to all diesel OBD-II equipped engines, but shows up more often in certain Chevy, Dodge, Ford and GMC trucks.
Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
The Diesel Intake Air Flow Control System (DIAFCS) is usually bolted to the intake manifold in the intake air stream. The DIAFCS system controls the amount of incoming airflow by varying a signal to a motor operated by the Powertrain Control Module (PCM). The motor opens and closes a throttle plate which regulates the airflow.
The PCM knows how much clean, filtered air is entering the engine based upon the Diesel Intake Airflow Position Sensor, also known as a MAF sensor. When the air flow control system is activated, the PCM should note a change in airflow. If not, then there may be something wrong with the DIAFCS system, or there may be something wrong with the MAF sensor. These codes are set if this input does not match normal engine operating conditions stored in the PCM’s memory, even for a second, as these diagnostic trouble codes demonstrate. It also looks at the voltage signal from the DIAFCS to determine if it is correct at initial Key On.
The code P02E4 Diesel Intake Air Flow Control Stuck Open is set when there is a detected stuck open condition of the diesel intake air flow control. It could have been set because of mechanical (physical damage to the control system itself, thereby causing an electrical fault) or electrical (DIAFCS motor circuit) issues. These cannot be overlooked in the troubleshooting stage, especially when dealing with an intermittent problem.
Troubleshooting steps may vary depending upon manufacturer, type of DIAFCS motor/control and wire colors.
What is the severity of this DTC?
Severity in all cases will be not severe. If mechanical issues are the cause, the typical failure is low idle speed. If it is an electrical failure, the PCM can compensate adequately for them.
What are some of the symptoms of the code?
Symptoms of a P02E4 trouble code may include:
Malfunction Indicator Light On Possible low idle speed only Flashing Electronic Throttle Control symbol No Regeneration of the diesel particulate filter to burn off the soot build up (won’t burn off soot out of the DPF catalyst) – eventual loss of power complainWhat are some of the common causes of the code?
Causes for this P02E4 code may include:
Open in the signal circuit to the DIAFCS motor/control – possible Short to voltage in the signal circuit to the DIAFCS motor/control - possible Short to ground in the signal circuit to the DIAFCS motor/control – possible Failed DIAFCS motor/control – likely Failed PCM - unlikelyWhat are some P02E4 troubleshooting steps?
A good starting point is always to check for technical service bulletins (TSB) for your vehicle. Your issue may be a known issue with a known fix put out by the manufacturer and can save you time and money during diagnosis.
Next, locate the DIAFCS motor/control system on your vehicle. This motor/control is usually bolted to the intake manifold in the intake air stream. Once located, visually inspect the connector and wiring. Look for scraping, rubbing, bare wires, burn spots or melted plastic. Pull the connector apart and carefully inspect the terminals (the metal parts) inside the connector. See if they look burned or have a green tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning of the terminals is needed. Let dry and apply electrical grease where the terminals contact.
If a mechanical code was set, use intake
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