P0451 on a Honda: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

You can keep driving a Honda with P0451 — it's an emissions fault, not an engine problem — but fix it before your next emissions test.

What P0451 means on a Honda

On a Honda, P0451 means the fuel tank pressure sensor in the EVAP system is reporting a reading that's outside the expected range. The sensor monitors tank pressure so the computer can check the evaporative emissions system for leaks. A bad reading usually just turns on the check engine light.

Is P0451 common on Hondas?

P0451 shows up on Hondas as the fuel tank pressure sensor ages, most often on higher-mileage Civics, Accords, and CR-Vs. Wiring issues and a sticking vent valve can also cause the code. It is an emissions problem and does not affect engine performance.

Commonly reported on: Civic, Accord, CR-V, Pilot.

Symptoms

Check engine light on
Possible faint fuel smell
No change in how the car drives

Common causes

most common: Faulty fuel tank pressure sensor
common: Damaged wiring or loose connector
common: Stuck or faulty EVAP vent valve
less common: Pinched or cracked EVAP hose

How to fix it

Fix	DIY?	Typical cost
Inspect the sensor wiring and connector	Yes	$10–50
Replace the fuel tank pressure sensor	Yes	$90–250
Have a smoke test done if the code returns	Mechanic	$50–150