This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.
P1518 is an OBD-II Code that refers to Intake Manifold Runner Control Fault Stuck Open (Ford, Lincoln, Mercury)
A P1518 code is a manufacturer specific diagnostic trouble code that occurs when the PCM/ECM detects a problem with the IMRC. Each cylinder has two intake air passages, which are made of aluminum and one passage is always open while the other is opened and closed with a butterfly valve plate. The housing employs a return spring to keep the plates shut. The motorized actuator houses internal switches to provide feedback to the Powertrain Control Module (PCM), indicating linkage and plate position.
This will allow a vacuum to vent from the actuator and the butterfly valve plates to open. The Diagnostic Trouble Code (DTC) sets when the IMRC is commanded close, but the IMRC monitor indicates open.
Common causes for this code include:
- The intake manifold runner control (IMRC) actuator is faulty.
- The intake manifold runner control actuator harness is open or damaged.
- Ineffective electrical connection in the intake manifold runner control actuator circuit
- Bad Powertrain Control Module (PCM)
The symptoms of a P1518 code are:
- Poor engine performance
- Illuminated check engine light
To diagnose a P1518 DTC code, a technician would:
- Scan for codes in the ECM and look at the freeze frame data for failure.
- Visually inspect the IMRC for damage.
- Check for voltage at the IMRC connector.
- Test the IMRC actuator for resistance and proper operation.
- Check the intake manifold runner control (IMRC) valve position with a scan tool.
- Check the PCM for other fault codes.
The following are some of the most common mistakes that a technician may make when diagnosing a P1518 code:
- Not thoroughly inspecting the IMRC for damage.
- Not checking for voltage at the IMRC connector.
- Testing the IMRC actuator for resistance and proper operation without first checking the battery.
- Not checking the intake manifold runner control (IMRC) valve position with a scan tool.
- Not clearing codes and performing a drive cycle before conducting further tests.
How serious is this?
A P1518 code is considered to be not serious. However, it can cause poor engine performance and an illuminated check engine light and should be addressed at your earliest convenience.
What repairs can fix the code?
The following are solutions that may fix this problem:
- Repair or replace the intake manifold runner control actuator.
- Repair or replace the intake manifold runner control actuator harness.
- Replace the PCM.
- Clean or replace the IMRC valve.
- Perform a drive cycle.
A P1518 is related to and may be accompanied by the following codes:
DTC P1517: Intake Manifold Runner Control Input Error Bank 2
DTC P1519: Intake Manifold Runner Control Fault Stuck Closed
DTC P1520: Intake Manifold Runner Control Circuit Fault
In conclusion, the P1518 code is a diagnostic trouble code that refers to a problem with the IMRC. This code can cause poor engine performance, an illuminated check engine light, and should be addressed at your earliest convenience. The most common repairs for this code include repairing or replacing the intake manifold runner control actuator, the intake manifold runner control actuator harness, or the PCM as a last resort.