Technical Description of OBD-II Trouble Code
The circuit for the Intake Manifold Runner Position Sensor / Switch on Bank 1 is experiencing intermittent issues.
What does that mean?
This particular diagnostic trouble code is applicable to fuel injected engines from various 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 assists the vehicle’s PCM in controlling the amount of air entering the engine at different RPMs. This code specifically pertains to Bank 1, which consists of cylinder number 1. The issue can be either a mechanical or electrical circuit fault, depending on the vehicle manufacturer and fuel system.
The troubleshooting steps may vary depending on the manufacturer, type of fuel system, and the type of intake manifold runner control valve/position (IMRC) sensor and wire colors.
Symptoms
The symptoms associated with a P2018 engine code may include:
Causes
The typical causes for this code to be triggered are:
(programming required after replacement)
Diagnostic Steps and Repair Information
It is always advisable 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 most common failure items (and often misdiagnosed items) in these systems are the IMRC vacuum solenoids, which can accumulate carbon and hinder proper venting, and the IMRC plates sticking or binding due to carbon deposits.
First, check for any other diagnostic fault codes. If there are any intake/engine performance system related codes, diagnose them first. Misdiagnosis can occur if this code is diagnosed before thoroughly diagnosing and dismissing any intake/engine performance related system codes. Ensure there are no intake or exhaust leaks, as an intake or vacuum leak can cause the engine to run lean, and an exhaust leak can give the impression of a lean running engine based on the air fuel ratio/oxygen (AFR/O2) sensor.
The next step is to locate the IMRC valve/sensor on your specific 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. Separate the connectors and carefully examine the terminals inside. Check 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, allow them to air dry. Apply dielectric silicone compound to the connector cavity and reassemble.
If you have a scan tool, clear the diagnostic trouble codes from memory and check if this code reappears. If it does not, then the issue was most likely related to the connections.
If the code does reappear, you will need to test the voltage signals to and from the IMRC valve/sensor using a scan tool or a digital volt ohm meter (DVOM). With the sensor connected, monitor the IMRC sensor voltage on the scan tool or test the signal with the DVOM. The IMRC sensor signal should change as the engine RPM increases. Refer to the manufacturer’s specifications for the expected voltage at a given RPM.
If the IMRC sensor fails this test, you will need to verify that the IMRC valve moves smoothly without binding or sticking inside the intake manifold. Remove the IMRC sensor/actuator and check for any binding or looseness in the plates/valves inside the intake manifold. If there is any binding, the plates/valves will need to be replaced, which usually requires replacing the entire intake manifold. It is recommended to seek professional assistance for this task.
If the IMRC plates/valves turn without binding or excessive looseness, it indicates the need to replace the IMRC sensor/actuator and retest.
Once again, it is crucial to diagnose any other codes before addressing this one, as issues that trigger other codes can also trigger this code. It is also advisable to consult with an automotive professional for the repair of your vehicle, especially if the problem is not obvious after the initial diagnosis steps. Most repairs beyond that point involve removing and replacing the intake manifold to correctly address this code and the related engine performance issue.
