What causes P1608 on a Honda?

Internal ECM fault in the IMA-CAN driver circuit Shorted IMA-CAN lines back-feeding the ECM Corroded ECM connector pins on the IMA-CAN terminals Failed ECM power or ground supply mimicking an internal fault Outdated ECM software mishandling IMA-CAN traffic

How do I fix P1608 on a Honda?

Inspect ECM connectors and IMA-CAN wiring for shorts before replacing anything Verify ECM power and ground circuits under load Check for Honda service bulletins covering an ECM software update Monitor IMA-CAN traffic with a Honda HDS scan tool Substitute a known-good ECM only after wiring and power are proven good

P1608 ECM Internal Integrated Motor Assist Controller Area Network Communication Circuit Malfunction

Q: What does P1608 mean on a Honda?

P1608. ECM Internal Integrated Motor Assist Controller Area Network Communication Circuit Malfunction. Applies to Insight, Civic Hybrid with IMA.

Category: Powertrain - Hybrid Propulsion
Severity: Check Engine Light
Applies to: Insight, Civic Hybrid with IMA

What does P1608 mean on a Honda?

P1608. ECM Internal Integrated Motor Assist Controller Area Network Communication Circuit Malfunction. This Honda-enhanced code applies to Insight, Civic Hybrid with IMA.

Common causes of P1608

Internal ECM fault in the IMA-CAN driver circuit
Shorted IMA-CAN lines back-feeding the ECM
Corroded ECM connector pins on the IMA-CAN terminals
Failed ECM power or ground supply mimicking an internal fault
Outdated ECM software mishandling IMA-CAN traffic

How to fix P1608

Inspect ECM connectors and IMA-CAN wiring for shorts before replacing anything
Verify ECM power and ground circuits under load
Check for Honda service bulletins covering an ECM software update
Monitor IMA-CAN traffic with a Honda HDS scan tool
Substitute a known-good ECM only after wiring and power are proven good

Sources and review

Last updated 2026-09-07.