What causes P1634 on a Honda?

Open or shorted signal wiring between the MPI module and the MCM Failed motor power inverter module driver stage Corroded high-voltage-adjacent signal connectors Overheated inverter from a failing cooling path Blown IMA system fuse cutting inverter signal power

How do I fix P1634 on a Honda?

Inspect inverter signal wiring and connectors for heat damage or corrosion Check IMA fuses and the inverter cooling path first Monitor inverter signals with a Honda HDS scan tool Follow Honda high-voltage safety precautions before touching inverter hardware Replace the inverter module only after the circuit tests bad end to end

P1634 Motor Power Inverter Module Signal Circuit Malfunction

Q: What does P1634 mean on a Honda?

P1634. Motor Power Inverter Module Signal 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 P1634 mean on a Honda?

P1634. Motor Power Inverter Module Signal Circuit Malfunction. This Honda-enhanced code applies to Insight, Civic Hybrid with IMA.

Common causes of P1634

Open or shorted signal wiring between the MPI module and the MCM
Failed motor power inverter module driver stage
Corroded high-voltage-adjacent signal connectors
Overheated inverter from a failing cooling path
Blown IMA system fuse cutting inverter signal power

How to fix P1634

Inspect inverter signal wiring and connectors for heat damage or corrosion
Check IMA fuses and the inverter cooling path first
Monitor inverter signals with a Honda HDS scan tool
Follow Honda high-voltage safety precautions before touching inverter hardware
Replace the inverter module only after the circuit tests bad end to end

Sources and review

Last updated 2026-09-07.