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P2172 OBD-II Trouble Code: Throttle Actuator Control System - Sudden High Airflow Detected

Check Engine Light

P2172 code definition

Throttle Actuator Control System - Sudden High Airflow Detected

What the P2172 code means

The P2172 code means that a large amount of airflow was suddenly inducted into the throttle actuator control system. The electronic control unit (ECU) detects this large amount of air and the P2172 diagnostic trouble code (DTC) is set. When the code is set, the Check Engine Light will be illuminated on the dashboard. When the code is set, the ECU will enable a failsafe mode to prevent any further damage. The failsafe mode will remain until the code is repaired or normal operation is detected.

What causes the P2172 code?

  • Stuck-open throttle plate
  • Manifold absolute pressure (MAP) sensor failure
  • Failed throttle body
  • Vacuum leak
  • Open or short in the wiring harness

What are the symptoms of the P2172 code?

How does a mechanic diagnose the P2172 code?

  • Qualified technicians will check for any codes stored in the vehicle's ECU first. These codes may include pending and history codes.

  • The freeze frame data found with any codes will also be stored in the ECU and will be noted.

  • Then all codes will be cleared and a test drive performed.

  • After the test drive, a visual inspection will be performed to look for any obvious faults.

  • The technician will use a multimeter to check for proper voltage at the MAP sensor.

  • Then the scan tool will be used to check the datastream and look at the fuel trims for a sign of a vacuum leak.

  • If a vacuum leak is suspected the intake system will be checked for vacuum leaks.

  • Lastly, the technician will remove the intake tube and inspect the throttle body and make sure it can operate.

Common mistakes when diagnosing the P2172 code

WIth many different systems having the potential to cause the P2172 code, it is easy for mistakes to be made. The most common mistake is confusing MAP sensor failure with a vacuum leak as they can have similar symptoms.

How serious is the P2172 code?

The P2172 code may prevent the vehicle from operating at all. This code has the potential to have no throttle response or not start at all. In cases where these occur, the vehicle should not be driven at all until repairs are made as it is not safe.

What repairs can fix the P2172 code?

  • Replacing the throttle body
  • Replacing the MAP sensor
  • Repairing a vacuum leak
  • Resolving an open or short in the wiring harness
  • Getting a sticking throttle body unstuck

Additional comments for consideration regarding the P2172 code

In some cases the throttle plate may be stuck open causing the P2172 code. If the throttle plate is stuck open there are usually 2 causes:

  1. mechanical failure
  2. carbon buildup that prevents the throttle from closing

The carbon buildup can be removed using throttle body cleaners to carefully dissolve the carbon and free up the throttle plate movement. Most of the time, the throttle is attempted to be cleaned before it is replaced as this is a much cheaper option.

Need help with a P2172 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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