P1661 Output Circuit Check Signal Low

Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: F-150, Mustang, Explorer, Ranger

What does P1661 mean on a Ford?

P1661 — Output Circuit Check Signal Low. This Ford-enhanced code applies to F-150, Mustang, Explorer, Ranger.

Common causes of P1661

Output circuit shorted to ground
Open output driver
Blown output fuse
Damaged harness
PCM fault

How to fix P1661

Check related fuses
Test for shorts to ground
Verify output continuity
Inspect harness routing
Repair the circuit