Technical Description of OBD-II Trouble Code
The circuit for the Intake Manifold Runner Position Sensor / Switch in Bank 2 is experiencing low voltage.
What does that mean?
This generic diagnostic trouble code is applicable to fuel injected engines from most manufacturers since 2003.
These manufacturers include Ford, Dodge, Toyota, Mercedes, Volkswagen, Nissan, and Infiniti.
This code primarily focuses on the value provided by the intake manifold flow control valve/position sensor, also known as the IMRC valve/sensor. It is typically located at one end of the intake manifold and helps the vehicle’s PCM regulate the amount of air entering the engine at different RPMs. This code specifically pertains to Bank 2, which consists of cylinders excluding cylinder number 1. Regardless of the vehicle manufacturer and fuel system, this code indicates an electrical circuit malfunction.
The troubleshooting steps may vary depending on the manufacturer, type of fuel system, and the type of intake manifold runner control valve/position sensor (IMRC) and wire colors.
Symptoms
The symptoms of a P2021 engine code may include:
Causes
The typical causes for this code to set are:
Diagnostic Steps and Repair Information
A good starting point is to check for technical service bulletins (TSB) specific to your vehicle. There may be a known issue with a known fix provided by the manufacturer, which can save time and money during diagnosis.
The next step is to locate the bank 2 IMRC valve/sensor in your vehicle. Once located, visually inspect the connectors and wiring for any signs of damage such as rubbing, scraping, bare wires, worn spots, or melted plastic connectors. Disconnect the connectors and examine the terminals inside for any signs of burning or corrosion. If necessary, clean the terminals using Electrical Contact cleaner or rubbing alcohol and a small plastic bristle brush. After cleaning, let them air dry and apply dielectric silicone compound to the connector cavity before reassembling.
If you have a scan tool, clear the diagnostic trouble codes from memory and check if this code returns. If it does not, then the issue was most likely related to the connections.
If the code does return, you will need to test the voltage signals to and from the PCM for the IMRC valve. Monitor the IMRC valve voltage using a scan tool. If a scan tool is not available, you can test the signal going to the IMRC valve using a digital volt ohm meter (DVOM). With the valve disconnected, connect the red voltmeter lead to the IMRC valve power wire and the black voltmeter lead to ground. Turn the ignition switch to the “run” position and check for voltage, which should be close to battery voltage (12 volts). If not, there is a problem with this circuit. If it does have 12 volts, reconnect the wires to the valve and check for voltage on the ground wire (PCM control wire), which should also be close to battery voltage. If not, the IMRC valve/solenoid is suspected to be open or shorted at this time.
If all testing has passed so far and the code still persists, check if your scan tool can open and close the IMRC valve. This may be referred to as an “Actuator Test,” “Bi-Directional Test,” or a “Functional Test” depending on the scan tool and vehicle manufacturer. If the scan tool has this capability and can operate the IMRC valves, then the problem is either resolved and only requires clearing the code, or a new PCM may be necessary. If the scan tool has the capability but is unable to move the valves, it indicates a defective ground circuit between the valve and the PCM or a defective PCM.
It is important to note that if the initial diagnostic steps do not reveal the problem, it is advisable to consult with an automotive professional for further repair, as diagnosing this code and the related engine performance issue may require the removal of the intake manifold.
