What does it mean?
P1418 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Secondary Air Injection System Control Circuit Shorted .
Symptoms
- MIL on, often with related secondary air codes stored together
- Air pump either runs constantly or never runs at all
- Blown fuse in the air injection circuit, sometimes repeatedly
- Rough idle and elevated emissions during cold start
- Burnt smell or visible harness damage in severe cases
Likely causes
- Control wire chafed to ground against a bracket, exhaust shield or body panel
- Internally shorted solenoid or relay coil in the air injection control circuit
- Water or salt intrusion in a connector bridging two pins
- Melted harness insulation where the wiring routes too close to the exhaust
- Crushed harness section at a clip or grommet after previous repair work
- Corroded relay socket creating a low resistance path between terminals
- Faulty PCM output driver, considered only when the external circuit tests clean
How to fix it
- Inspect the harness along its full route for melted, chafed or crushed insulation, especially near exhaust components
- Disconnect the solenoid or relay and measure the control wire resistance to ground; a very low value confirms a short
- Unplug the PCM connector as well to separate a harness short from an internal module fault
- Measure the coil resistance of the controlled device against specification to find an internally shorted winding
- Check the connector cavities for moisture, corrosion and terminal pushback
- Repair the shorted wire properly with heat resistant insulation and correct routing, not just tape
- Replace the shorted solenoid or relay if needed, replace any blown fuse, then verify normal pump operation on a cold start