P2021 trouble code definition
Intake Manifold Runner Position Sensor/Switch Circuit Low Bank 2
It should be noted that this code can have a different description if the vehicle has a diesel engine. If that is the case, the definition would be “Rail Pressure Monitoring VIA Pressure Control Valve, pressure low”. Not as common as the gas code definition, but still in use on some vehicles.
What the P2021 code means
Circuit Low Bank 2 is stating the circuit has lower value than the PCM (powertrain control module) expects. The resistance or voltage in the sensor changes as the valve position changes.
There is typically an actuator or solenoid that redirects the path of air traveling through the intake manifold to the cylinders. The changing intake runner length is used to optimize air flow through the intake manifold as RPM (revolutions per minute) change.
What causes the P2021 code?
This code is set when the PCM sensor monitoring the intake runner valve position is not in the expected position. Most often the computer is watching a changing resistance or voltage value that increases or decreases depending on the valves position.
What are the symptoms of the P2021 code?
Usually there is a drivability concern noticed by the owner. The vehicle can exhibit a variety of symptoms depending on the type of system being used:
- Erratic idle
- Lack of power
- Engine won’t rev as high as usual
- Engine stall
- Check Engine Light
- Vacuum leak
How does a mechanic diagnose the P2021 code?
The technician will first connect a scanner to the vehicle to either command the system on or simply to monitor the system data.
Often times a handheld vacuum pump will be used to test one or more vacuum operated actuators. If the system is actuated electrically then the components will often be referred to as a solenoid or motor.
Regardless of the technology, the technician is monitoring the intake to see if the internal valve is being turned by the solenoid, actuator or motor. This can be accomplished by commanding the system on with the scanner or driving the vehicle under the conditions necessary to activate the system and watch the scan tool data.
Many times it is necessary to disassemble the intake to see if the intake runner valve is stuck.
Common mistakes when diagnosing the P2021 code
These systems are fairly simple in their design and function, although the rationale for their use is often misunderstood. For this reason a mechanic will often miss other problems with the motor that will affect the operation of this system.
How serious is the P2021 code?
Other than the inconvenience of erratic drivability symptoms, problems with this system will not likely cause any permanent damage to the motor. Although the symptoms will likely be noticeable enough to force the owner to seek a repair shop sooner than later. Driving a vehicle with this system impaired will most likely be frustrating.
What repairs can fix the P2021 code?
Usually it is a broken diaphragm inside a vacuum controlled actuator that needs to be replaced. However, other possibilities are:
- Replace electric valve solenoid
- Replace valve position sensor
- Replace the vacuum valve actuator
- Repair poor connections at electrical connections
- Repair any vacuum leaks
- Replace broken vacuum hoses
- Repair other components that can affect the intake manifold pressures
Additional comments for consideration regarding the P202 code
Each manufacturer utilizes different strategies when designing a VIM system (variable intake manifold). For this reason terminology will differ between manufacturers. This particular code is for bank 2. This indicates there are likely two sensors for this engine. Bank 2 would be the sensor on the intake runner that supplies air to the bank of cylinders not including number one cylinder.
This code specifically monitors the variable intake manifold valve position sensor. The sensor is used by the PCM to know what position the VIM valve is in. If this valve is not in the position the PCM is expecting for the present engine conditions, code P2021 will be set. It should be noted, if the motor has only one bank of cylinders, this code will not be utilized for that particular vehicle.
Need help with a P2021 code?
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