Intake Air Control Circuit Malfunction
Findings, check these first
- Open or shorted IAC valve windings
- Carbon-locked IAC pintle
- Damaged IAC wiring or connector
- Blown IAC circuit fuse
- PCM driver fault
Standard procedure
- Measure IAC winding resistance against spec
- Remove and clean carbon from the valve and passages
- Check fuse and supply voltage at the valve
- Inspect wiring and connector
- Replace the valve after confirming power and command
Code lookup
Type a code above, or start from a symptom or a common code.
Press / to jump to the box. Ford-enhanced powertrain, body, chassis and network codes. Generic P0xxx codes live on OBD Codes List.
Sources and review
Review: checked against the recorded source material.
- OBDII.pro: P1504 Ford definition
live reference page (obdii.pro)
Supports: Ford-family meaning for P1504: Idle Air Control Circuit Malfunction
Fetched directly. obdii.pro is a publisher independent of the engine-codes family.
- P1504 FORD Code: Meaning, Causes, and Symptoms | OBD2 Codes
live reference page (obd2-codes.co)
Supports: Ford meaning for P1504: Intake Air Control Circuit Malfunction
Fetched directly. obd2-codes.co phrasing matches the engine-codes family, so it counts as one publisher.
Last updated 2026-09-04.
Report a correction for P1504. Include your vehicle, the issue and a source if you have one.