|Code||Fault Location||Probable Cause|
|P2012|| Intake manifold air control actuator / solenoid, bank 2- circuit low |
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|Wiring short to ground, intake manifold air control actuator / solenoid|
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What Does Code P2012 Mean?
OBD II fault code P2012 is a generic code that is defined as “Intake manifold air control actuator / solenoid, bank 2- circuit low”, and is set when the PCM (Powertrain Control Module) detects an abnormally low voltage in the IMRC (Intake Manifold Runner Control) system actuator/solenoid control circuit, or a general failure of the electrical control circuit that prevents effective communication between the IMRC actuator/solenoid and the PCM. “Bank 2” refers to the IMRC control system on the bank of cylinders that does not contain cylinder #1. Note that code P2012 refers specifically to low voltages in the control circuit of the IMRC actuator/solenoid and not to general mechanical failures/issues in the system.
NOTE #1: The IMRC should not be confused with a similar system that tweaks or controls inlet manifold dynamics, which effectively changes the length of individual manifold runners. Since the IMRC system controls the motion of the intake air inside the inlet manifold, the ISO/SAE recommended term for this system is “Intake Manifold Runner Control System”(IMRC), to avoid confusion, although this system is sometimes also known as the Swirl Control System/Valve or the Charge Motion Control System/Valve.
NOTE #2: Similarly, the ISO/SAE recommends that all systems/devices that control, regulate, tweak, or alter the dynamics(length, shape, or diameter) of inlet manifold runners be referred to as the “Intake Manifold Tuning (IMT) Valve”, although this system is sometimes also known as the Intake Manifold Tuning Valve, Long/Short Runner Control, or Intake Manifold Communication Control.
The purpose of the intake manifold runners is to improve the airflow inside the intake manifold by creating a restriction in the manifold at low engine speeds, both to improve engine efficiency at low engine speeds, and to reduce harmful exhaust emissions. Since combustion is typically less efficient at low engine speeds, creating a partial restriction in each manifold runner increases the airflow rate through the runners, which has the effect of eliminating manifold pressure fluctuations that are caused by the opening and closing of the inlet valves during normal engine operation.
In terms of operation, the IMRC system uses individual flaps in each manifold runner that are all connected to a control rod that runs the length of the inlet manifold. The control rod is connected to an actuator that can be eclectically or vacuum operated; by activating the actuator, all the flaps in the manifold move by the same amount. Note however, that the runner flaps never close off the runners completely; depending on the application, most systems only close off around 60% of the diameter of the inlet manifold runners.
To control and monitor the position of the manifold runner flaps, the PCM uses input data from the MAF (Mass Airflow) sensor, barometric pressure sensor, engine sped sensor, IAT (Intake Air Temperature) sensor, TPS (Throttle Position) sensor(s), and others to calculate an appropriate setting for the manifold runner flaps to suit current operating conditions. To be sure that the desired and actual positions of the runner flaps coincide, the PCM also uses input data from a dedicated position switch that communicates the actual position of the runner flaps to the PCM via a dedicated signal circuit.
From the above it should be obvious that effective communication between the PCM, the IMRC system actuator, and the IMRC system position switch is vital for the correct operation of the system, since IMRC flaps generally do not have a default open position. In practice, this means that if the system fails in the closed position, it will remain in that position until the failure is corrected.
Therefore, as soon as the PCM detects an abnormally low voltage anywhere in the control system of the IMRC system actuator/solenoid that prevents effective communication between the PCM and the IMRC system actuator/solenoid, it will set code P2012 and illuminate a warning light.
Where is the P2012 sensor located?
The image above shows the typical appearance of an IMRC system, but note that in this instance, the system is operated by a vacuum controlled actuator, which is indicated by the yellow arrow. The green arrow indicates the electrical connector of the position switch, the red arrows indicate individual runner flaps, and the blue arrow indicates the linkage that connects the actuator to the control rod.
Note though that depending on the application, the actual design, appearance, layout, and arrangement of individual components may differ greatly from the example shown here. For this reason, it is important to refer to the manual for the affected application to locate and identify parts/components correctly- failure to do this will almost certainly result in confusion, wasted time, misdiagnoses, and the unnecessary replacement of parts and components.
What are the common causes of code P2012?
Some common causes of code P2012 could include the following-
- Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors
- Bad connections across one or more connectors
- Defective IMRC position switch
- Defective IMRC actuator if the actuator is electrically operated
- Failed or failing PCM. Note that this is a rare event, and the fault must therefore be sought elsewhere before any control module is replaced
NOTE: It should be noted that while the causes listed above are the most common, failures of, and defects in associated sensors and their control circuits can sometimes cause, or contribute to the setting of code P2012. However, since these defects and failures will almost invariably be indicated by codes that relate directly to the failure, it is important to resolve all additional codes in the order in which they were stored to prevent a misdiagnosis, and possibly the unnecessary replacement of parts and components.
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