What causes P1631 on a Toyota?

Open ECM-to-VSC communication line Corroded skid control connector Failing skid control ECU Software mismatch after module replacement Intermittent network dropout

How do I fix P1631 on a Toyota?

Scan both ECM and skid control ECU Check network communication health Verify module calibrations match Inspect connectors Reflash or replace modules per findings

P1631 Communication Error From ECM to VSC

Q: What does P1631 mean on a Toyota?

P1631. Communication Error From ECM to VSC. Applies to Camry, RAV4, Highlander with VSC.

Category: Network Communications
Severity: Check Engine Light
Applies to: Camry, RAV4, Highlander with VSC

What does P1631 mean on a Toyota?

P1631. Communication Error From ECM to VSC. This Toyota-enhanced code applies to Camry, RAV4, Highlander with VSC.

Common causes of P1631

Open ECM-to-VSC communication line
Corroded skid control connector
Failing skid control ECU
Software mismatch after module replacement
Intermittent network dropout

How to fix P1631

Scan both ECM and skid control ECU
Check network communication health
Verify module calibrations match
Inspect connectors
Reflash or replace modules per findings

Sources and review

Last updated 2026-09-06.