What causes P1549 on a Honda?

Failing voltage regulator overcharging the system Poor connections or loose terminals at the alternator Corroded ground straps raising charging voltage 24-volt jump-start or charger confusing the ECM Failing alternator diode pack

How do I fix P1549 on a Honda?

Measure charging voltage at the battery. Sustained readings at or above 16 volts confirm it Inspect alternator connections and under-hood grounds for looseness and corrosion Check whether a 24-volt source was ever connected. That alone can set this code Test the alternator output and regulator response under electrical load Replace the alternator if voltage stays high with clean connections

P1549 Charging System High Voltage

Q: What does P1549 mean on a Honda?

P1549. Charging System High Voltage. Applies to Civic, Accord, CR-V.

Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: Civic, Accord, CR-V

What does P1549 mean on a Honda?

P1549. Charging System High Voltage. This Honda-enhanced code applies to Civic, Accord, CR-V.

Common causes of P1549

Failing voltage regulator overcharging the system
Poor connections or loose terminals at the alternator
Corroded ground straps raising charging voltage
24-volt jump-start or charger confusing the ECM
Failing alternator diode pack

How to fix P1549

Measure charging voltage at the battery. Sustained readings at or above 16 volts confirm it
Inspect alternator connections and under-hood grounds for looseness and corrosion
Check whether a 24-volt source was ever connected. That alone can set this code
Test the alternator output and regulator response under electrical load
Replace the alternator if voltage stays high with clean connections

Sources and review

Last updated 2026-09-20.