P206F Intake manifold tuning (IMT) valve stuck closed bank 2

P206F Intake manifold tuning (IMT) valve stuck closed bank 2

OBD-II DTC Datasheet

Intake Manifold Tuning (IMT) Valve Stuck Closed Bank 2

What does this mean?

This Diagnostic Trouble Code (DTC) is a generic transmission code and applies to many OBD-II vehicles (1996 and newer). This may include, but is not limited to, Mercedes Benz, Audi, Chevrolet, GMC, Sprinter, Land Rover, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model and transmission configuration.

A stored code P206F means the powertrain control module (PCM) has detected an intake manifold tuning valve (IMT) that is stuck closed for the second row of engines. Bank 2 refers to an engine group that does NOT contain cylinder number one.

The intake manifold tuning is used to limit and control intake air as it enters individual manifold openings. IMT not only regulates the intake air volume, but also creates a vortex movement. These two factors contribute to more efficient fuel atomization. Each port of the intake manifold is equipped with a metal flap; not much different from the throttle valve. A single shaft runs from one end of the manifold (for each row of engines) to the other and through the middle of each port. The metal dampers are attached to a shaft that will (slightly) rotate to open and close the dampers.

The IMT shaft is driven by the PCM. Some systems use an electronic super vacuum actuator (valve) system. Other systems use an electronic motor to move the dampers. The PCM sends the appropriate voltage signal and the IMT valve opens and closes the valve (s) to the desired degree. The PCM monitors the actual valve position to determine if the system is working properly.

If the PCM detects that the IMT valve is stuck closed, a P206F code will be stored and a malfunction indicator lamp (MIL) will illuminate. It may take multiple ignition failures to illuminate the MIL.

An example of an Intake Manifold Adjustment Valve (IMT):

What is the severity of this DTC?

Failure of the IMT system can adversely affect fuel efficiency and, in rare cases, lead to equipment being pulled into the combustion chamber. The conditions that led to the persistence of the P206F code should be eliminated as soon as possible.

What are some of the symptoms of the code?

Symptoms of a P206F trouble code may include:

• Reduced fuel efficiency
• Reduced engine power
• Lean or rich exhaust gas codes
• There can be no symptoms at all.

What are some of the common causes for the code?

Reasons for this code may include:

• Securing or loosening the IMT flaps
• Faulty IMT actuator (valve)
• Vacuum leak
• Open or short circuit in wiring or connectors
• Defective PCM or PCM programming error

What are some steps to troubleshoot the P206F?

To diagnose the P206F code, you will need a diagnostic scanner, a digital volt / ohmmeter (DVOM), and a source of vehicle-specific diagnostic information.

You can use your vehicle information source to find a Technical Service Bulletin (TSB) that matches your vehicle's year, make and model; as well as engine displacement, stored codes and symptoms detected. If you find it, it can provide useful diagnostic information.

Use a scanner (connected to the vehicle's diagnostic socket) to retrieve all stored codes and associated freeze frame data. It is recommended that you write down this information before clearing the codes and then test drive the vehicle until the PCM enters ready mode or the code is cleared.

If the PCM enters ready mode at this time, the code is intermittent and can be much more difficult to diagnose. In this case, the conditions that contributed to the retention of the code may need to worsen before an accurate diagnosis can be made.

If the code is reset immediately, the next diagnostic step will require you to search your vehicle information source for diagnostic block diagrams, pinouts, connector faceplates, and component test procedures / specifications.

Step 1

Use your vehicle diagnostic source and DVOM to test voltage, ground, and signal circuits at the appropriate IMT valve.

Step 2

Use the DVOM to test the appropriate IMT valve according to the manufacturer's specifications. Components that fail the test within the maximum allowable parameters should be considered defective.

Step 3

If the IMT valve is functional, use the DVOM to test the input and output circuits from the fuse panel and PCM. Disconnect all controllers before using the DVOM for testing.

• Defective IMT valves, levers and bushings are usually at the heart of codes associated with IMT.

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