P0543: Intake Air Heater A Circuit Open

What does P0543 mean?

P0543 is a diagnostic trouble code indicating "Intake Air Heater A Circuit Open". This means there is an electrical break in the intake system wiring — a connector may be unplugged, a wire broken, or a component has failed internally. The ECU detected no signal where it expected one.

Symptoms you may notice

• Check engine light (MIL) illuminated on dashboard
• Intermittent warning lights
• Erratic gauge readings

Common causes

• Damaged or corroded wiring harness
• Loose or disconnected electrical connector
• Failed intake system sensor or actuator
• Blown fuse in the related circuit
• Poor ground connection

What should you do?

This code sits in an engine peripheral, typically emissions or forced induction. It will not take braking or steering away, but it can put the car into limp mode, cost you fuel and fail a roadworthy. Book it in rather than clearing it and hoping.