P1533 AAI Circuit Malfunction

Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: Ford models with Air Assist Injection

What does P1533 mean on a Ford?

P1533 — AAI Circuit Malfunction. This Ford-enhanced code applies to Ford models with Air Assist Injection.

Common causes of P1533

Failed air assist injector
Open or shorted AAI circuit
Clogged air assist passages
Blown AAI fuse
Corroded connector

How to fix P1533

Check the AAI fuse
Test injector resistance
Inspect air passages for clogging
Verify command signal
Replace the injector after circuit checks