P02E8: Diesel Intake Air Flow Position Sensor Circuit Low

What Does The P02E8 Code Mean?

The Diesel Intake Air Flow Position Sensor (DIAFPS) is usually bolted to the throttle body mounted to the intake manifold or in a tube in the intake air stream.

The DIAFPS sensor converts the incoming airflow volume into an electrical signal for the Powertrain Control Module (PCM).

The PCM receives this voltage signal to determine how much clean, filtered air is entering the engine versus how much is entering through the exhaust system via the Exhaust Gas Recirculation System, or EGR System.

When the EGR system is activated, the PCM should note a change in airflow. If not, then there may be something wrong with the EGR system, or there may be something wrong with the DIAFPS, also known as a MAF sensor.

This code is 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 DIAFPS to determine if it is correct at initial Key On.

The code P02E8 Diesel Intake Air Flow Position Sensor Circuit Low is set when the voltage at the sensor stays below a set level (usually under 0.3V) for too long a period. This code is usually considered to be an electrical circuit issue.

Troubleshooting steps may vary depending upon manufacturer, type of DIAFCS motor/control and wire colors.

What Are The Symptoms Of The P02E8 Code?

Symptoms of a P02E8 trouble code may include:

• Malfunction Indicator Light On
• Possible low idle speed only
• No EGR System operation
• No Regeneration of the diesel particulate filter to burn off the soot build up (won’t burn off soot out of the DPF catalyst)

What Are The Potential Causes Of The P02E8 Code?

Causes for this P02E8 code may include:

• Short to ground in the signal circuit to the DIAFPS sensor – possible
• Failed DIAFPS Sensor – possible
• Failed PCM – unlikely

How Serious Is This P02E8 Code?

Severity in all cases will be not severe. Since they are electrical failures, the PCM can compensate adequately for them.

How Can You Fix The P02E8 Code?

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 DIAFPS sensor on your vehicle. This sensor is usually bolted to the throttle body mounted to the intake manifold or in a tube 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 you have a scan tool, clear the diagnostic trouble codes from memory, and see if P02E8 code returns. If it does not, then the connections were most likely your problem.

If the P02E8 code does return, we will need to test the DIAFPS sensor and its associated circuits. With the Key Off, disconnect the electrical connector at the DIAFPS sensor. Connect a Digital Voltmeter black lead to the ground terminal at the DIAFPS sensor wiring harness connector. Connect the red lead of the Digital Voltmeter to the signal terminal at the DIAFPS sensor wiring harness connector.

Turn Key On Engine Off. Check manufacturer’s specifications; voltmeter should read 5 volts. If not, repair the signal or ground wire, or replace the PCM.

If the prior test passed and you continue to get a P02E8, this would most likely indicate a failed DIAFCS sensor, although a failed PCM could not be ruled out until the DIAFCS sensor had been replaced.

If unsure, seek assistance from a trained automotive diagnostician. PCMs must be programmed, or calibrated to the vehicle to be installed correctly.

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> WORKPRO 582-piece Crimp Terminals, Wire Connectors, Heat Shrink Tube, Electrical Repair Kit
>>> Dorman 86689C 399 PC Automotive Electrical Repair Kit
>>> ECU
>>> INNOVA 5210
>>> KAIWEETS Digital Multimeter

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

P02E8: Diesel Intake Air Flow Position Sensor Circuit Low, OBD-Codes.