Possible causes

– Poor connection at the AC motor control module
– Open or short circuit condition
– Failed AC Motor Control Module

When is the code detected?

No duty signals are input from the MCM for at least 5 seconds.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1644 HONDA Description

The Motor Control Module (MCM) signals various information about the IMA system to the Engine Control Module (ECM) via the MOTFSA signal line. If no duty signals are input from the MCM for at least a set time period, the ECM detects a malfunction and stores a DTC.