|Code||Fault Location||Probable Cause|
|P200B|| Intake manifold air control actuator / solenoid, bank 2 - performance problem |
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|Wiring, intake manifold air control actuator / solenoid, ECM|
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What Does Code P200B Mean?
OBD II fault code P200B is a generic code that is defined as “Intake manifold air control actuator / solenoid, bank 2 – performance problem”, and is set when the PCM (Power Control Module) detects that the Intake Manifold Runner Control (IMCR) actuator and/or its control system is not performing as expected, given the available input data from various engine sensors. Note that “Bank 2” refers to the bank of cylinders that does not contain cylinder #1 on V-type engines
Performance issues with the IMCR actuator means that the manifold runner flap actuator is not controlling the manifold runner flaps as expected, which typically means that the flaps are either not opening/closing, or are opening/closing more or less than expected.
The purpose of the IMCR system is to alter the rate at which intake air enters the cylinders. By creating a restriction in each manifold runner the airflow rate is increased, which has the effect of improving fuel vaporization, which in turn, improves combustion and reduces exhaust emissions particularly at idle, or low engine speeds. Similarly, at higher engine speeds, the artificial restriction created by the IMCR system causes the air to “tumble” or swirl more than would have been possible without the IMCR system in place, which also causes improved combustion and reduced exhaust emissions since the air/fuel mixture is mixed more completely just before ignition of the mixture occurs.
In practice, the PCM uses input data from the MAP (Manifold Absolute Pressure) sensor, MAF (Mass Airflow) sensor, if equipped), IAT (Intake Air Temperature) sensor, TPS (Throttle Position sensor(s), and oxygen or air/fuel ratio sensors, and the engine speed sensor (among others) to calculate an appropriate setting for the manifold runner flaps. By varying the opening angle of the manifold runner flaps to suit prevailing operating conditions, engine performance is improved and exhaust emissions are reduced throughout the engine’s operating range.
This calculated setting is compared to the actual position of the manifold runner flaps as measured by a dedicated position sensor. If the PCM determines that the desired and actual positions of the manifold runner flap actuator differs by more than a predefined amount, it recognizes that the actuator is not performing as expected, and will set code P200B and may also illuminate a warning light as a result.
While design specifics vary between applications and manufacturers, all IMCR systems are essentially the same in terms of construction and operating principles. All systems consist of individual metal flaps that are all connected to a control rod that runs the length of the inlet manifold, which in turn, is connected to an actuator that can be either an electronically controlled DC stepper motor or an actuator that is operated by engine vacuum. Thus, all the flaps that are connected to the actuator via the control rod move by the same amount when the actuator is activated.
It should be noted however that the manifold runner flaps never close off the individual manifold runners completely. On most applications, the restriction only blocks off about 60% of the runners’ diameter, but this percentage varies between applications, models, and manufacturers. It should also be noted that IMCR systems generally do not have a default “open” setting to which the system defaults when a failure occurs. In practice, this means that if the system fails in the closed position, the manifold runner flaps will remain in the closed position until the failure is repaired or corrected. Therefore, depending on the IMCR position when the failure occurred, engine performance can be seriously reduced at some engine speeds, depending on the IMCR position when the failure occurred.
Where is the P200B sensor located?
The image below shows the typical arrangement of inlet manifold runner flaps in the inlet manifold.
In this example, the red arrows indicate the individual runner flaps in the fully open position; the yellow arrow indicates the vacuum operated actuator, the blue arrow indicates the rod connecting the actuator to the flap control rod, and the green arrow indicates the runner flap position sensor and its electrical connector.
Note that since the actual arrangement and construction of the IMCR system varies between applications, it is important to refer to the manual for the affected application for details on the correct procedure to follow to access the various components of the IMCR system on that particular application.
What are the common causes of code P200B?
Common causes of code P200B could include the following-
- Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors that can cause the PCM to receive inaccurate, invalid, or implausible input signals
- Dislodged, torn, ruptured, or otherwise damaged vacuum lines that supply vacuum to the IMCR actuator
- Defective IMCR position sensor that can transmit inaccurate input signals to the PCM
- Excessive carbon build-up or deposits that can inhibit free movement of the runner flaps
- Mechanical failure of one or more connecting rods
- Mechanical failure of the vacuum actuator
- Mechanical failure of the DC stepper motor on applications that control the IMCR system electronically
- Defective MAP sensor
- Defective MAF sensor
- Defective Intake Air Temperature sensor
NOTE: Some of the causes listed here may produce additional codes that relate to failures and/or malfunctions in one or more engine sensors and/or their control circuits. Therefore, when code P200B is encountered on any application, it is important to diagnose and resolve codes in the order in which they were stored. Failure to do this will result in a misdiagnosis, wasted time, and the unnecessary replacement of parts and components.