Technical Description of OBD-II Trouble Code
The intake manifold runner control for Bank 1 is stuck in the open position.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to all vehicles from 1996 onwards (Mazda, Ford, Dodge, Jeep, Kia, etc.). While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
If your OBD II equipped vehicle has a stored code P2004, it means that the powertrain control module (PCM) has detected that the intake manifold runner control (IMRC) actuator for engine bank one is stuck open. Bank 1 refers to the engine bank that contains the number one cylinder.
The PCM controls the IMRC system to manage and fine-tune the airflow as it enters the lower intake manifold, cylinder heads, and combustion chambers. The runner control solenoid opens and closes metal flaps that fit tightly into the intake port of each cylinder. These flaps are attached to a thin metal rod that runs through each intake port and the length of each cylinder head. If one of the flaps is stuck or binding, it can render all the flaps inoperative. The IMRC actuator is connected to the rod with a mechanical arm or gear. Some models use a vacuum diaphragm operated actuator, while others use an electronic solenoid controlled by the PCM to regulate intake vacuum to the IMRC actuator.
The IMRC system creates a swirling effect by channeling and restricting the airflow as it enters the engine. Research has shown that this swirling effect helps to atomize the air/fuel mixture more thoroughly, resulting in reduced exhaust emissions, improved fuel efficiency, and optimized engine performance. Different automakers use different IMRC methods, so it’s important to consult the vehicle information source to understand the specific IMRC system in your vehicle. Theoretically, the IMRC runners are partially closed during starting and idling conditions, and fully opened when the throttle plate is opened.
To ensure that the IMRC actuator is functioning correctly, the PCM monitors input signals from various sensors, including the IMRC runner position sensor, manifold absolute pressure (MAP) sensor, manifold air temperature sensor, intake air temperature sensor, throttle position sensor, oxygen sensors, and mass airflow (MAF) sensor.
Based on the input data, the PCM monitors the actual runner flap position and adjusts it as necessary. If the PCM does not detect a significant enough change in MAP or manifold air temperature in accordance with the desired repositioning of the flaps by the IMRC actuator, it will store a code P2004 and may illuminate the malfunction indicator lamp. In many cases, multiple ignition cycles with an IMRC actuator failure are required for the malfunction indicator lamp to illuminate.
Symptoms
Symptoms of a P2004 code may include:
Causes
Possible causes for this engine code include:
Diagnostic and Repair Procedures
When attempting to diagnose a code P2004, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source such as All Data DIY.
Before starting the diagnosis, check for any relevant technical service bulletins (TSB) that may provide information on the specific symptoms, stored codes, and make/model of the vehicle. If you find a related TSB, the information can assist you in diagnosing the P2004 code in your vehicle.
Begin the diagnosis with a visual inspection of the system wiring and connector faces. Pay close attention to the IMRC actuator connectors, as they are prone to corrosion that can cause an open circuit.
Next, connect the scanner to the vehicle diagnostic connector and retrieve all stored codes and freeze frame data. It is recommended to write down this information in case the code is intermittent. Clear the codes and test-drive the vehicle to see if the code is reset.
If the code is reset, access the IMRC actuator solenoid and IMRC runner position sensor. Consult the vehicle information source for testing recommendations for these components. Use the DVOM to perform a resistance test on both the actuator and the position sensor. If either component fails to comply with the manufacturer’s recommendations, replace the defective part and retest the system.
If both the actuator and sensor resistance comply with the manufacturer’s specifications, use the DVOM to test the resistance and continuity on all system circuits. Before testing, disconnect all related controllers to avoid damaging the controller. Repair or replace any shorted or open circuits as necessary.
Additional diagnostic notes:
