P1681 Automatic transmission FI signal A low input
What does P1681 mean on a Honda?
P1681. Automatic transmission FI signal A low input. This Honda-enhanced code applies to 1998 to 2002 Accord and Acura TL with automatic.
Common causes of P1681
- Short to ground on signal A wire
- Corroded signal A connector pin
- Failed FI signal A driver
- Weak system voltage
- Faulty ECM input circuit
How to fix P1681
- Check battery and grounds
- Inspect signal A wiring for shorts
- Test signal A voltage at both modules
- Repair the shorted wire found
- Replace the failed module if signal stays low
Sources and review
- Last updated 2026-09-24.