Intake Manifold Runner Position Sensor/Switch Circuit Intermittent Bank 1
This code indicates that the powertrain control module (PCM) has detected an intermittent or erratic electrical signal from the intake manifold runner position sensor on Bank 1. The PCM sets this code when the sensor's voltage output drops out or fluctuates outside of expected parameters, suggesting a loose connection or failing sensor.
While not an immediate safety hazard, this issue can cause poor engine performance, reduced fuel economy, and increased emissions. It should be diagnosed and repaired soon to restore proper drivability and prevent potential long-term engine inefficiency.
Common symptoms
- Illuminated Check Engine Light
- Engine hesitation or stumble during acceleration
- Rough or fluctuating idle
- Noticeable decrease in low-end engine torque
- Reduced fuel efficiency
Likely causes
- Loose, damaged, or corroded wiring and connectors at the IMRC sensor
- Faulty intake manifold runner position sensor
- Carbon buildup causing the intake manifold runner flaps to stick or bind
- Faulty IMRC actuator or control solenoid
- Vacuum leaks in the IMRC control system (if vacuum-actuated)
What to check before replacing parts
Visually inspect the wiring harness and connector at the Bank 1 IMRC sensor.
Look for: Look for loose pins, corrosion, frayed wires, or signs of heat damage that could cause an intermittent connection.
Monitor the IMRC sensor voltage with a scan tool while gently wiggling the wiring harness.
Look for: If the voltage reading drops out or spikes erratically while moving the wires, there is a loose connection or internal wire break.
Manually actuate the intake manifold runner linkage.
Look for: Check for physical binding, excessive resistance, or sticking caused by carbon buildup inside the manifold.
Test the IMRC position sensor resistance and voltage using a digital multimeter.
Look for: Compare the readings to the manufacturer's specifications; an out-of-range or fluctuating reading indicates a failing sensor.
Inspect the vacuum lines and control solenoid (if the system is vacuum-actuated).
Look for: Look for cracked, disconnected, or leaking vacuum hoses that could cause the runner flaps to flutter or move erratically.
This page explains the generic P2018 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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