Honda P1457 Code: EVAP Control System Leakage (EVAP Canister Area)
Honda's EVAP self-test found a leak on the charcoal canister side, not at the fuel tank or gas cap.
Safety first · Consult a professional
- Fuel vapor is flammable. No smoking or open flames; work outdoors and fix fuel leaks before driving.
At a glance
Severity: Low
- Meaning
- EVAP Control System Leakage (EVAP Canister Area)
- System
- Emission Controls · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $40–$750
- DIY difficulty
- Moderate
Honda runs its EVAP leak check in two halves, split by a two-way valve and a bypass solenoid near the tank. P1457 means the PCM closed the canister vent shut valve, pulled a vacuum with the purge valve, and saw it decay too fast on the canister half: the charcoal canister, the vent shut valve and its filter, the purge valve and the lines that link them. Unlike P1456, the gas cap is rarely the culprit here. On Civics, Accords, CR-Vs, Odysseys and Pilots from salt-belt states, a corroded vent shut valve mounted next to the canister under the rear of the car is the classic find.
Can I keep driving? Driving is safe and the engine runs normally. The only real concern is a raw gasoline smell, which points to a larger leak or a cracked canister and should be checked soon.
How to read P1457
- P Powertrain
- 1 Manufacturer-specific
- 4 Auxiliary emission controls
- 57 Specific fault
Symptoms
- Check engine light on with no change in how the car drives
- Code returns a few days after clearing, once the EVAP monitor runs again
- Faint fuel vapor smell near the rear wheels or under the car, sometimes
- EVAP monitor shows incomplete or failed on a readiness check
- Occasionally slow fueling or pump shut-off if the vent path is also restricted
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Canister vent shut valve corroded, stuck open or leaking at its seal
- Cracked or loose hose between the canister, vent valve and purge line
- Purge control solenoid leaking or not sealing when closed
- Charcoal canister housing cracked or damaged by road debris
- Two-way valve or bypass solenoid fault letting the halves talk to each other
- Wiring or connector fault at the vent shut valve
Diagnosis step by step
Find the canister and vent shut valve
On most Hondas both sit under the rear of the car near the fuel tank, often above the rear suspension or behind a plastic splash shield. Look at the vent shut valve first: a bubbled, rusty metal body or a cracked plastic nipple is a strong hint.
Tools: Flashlight, Gloves
Check the vent shut valve operation
The valve is normally open. Unplugged, you should be able to blow through it; with 12 V applied briefly across its terminals it should click shut and hold vacuum from a hand pump. If it leaks when energized, replace it.
Tools: Multimeter, Vacuum gauge
Check the purge valve seal
The purge solenoid is normally closed. With the engine off and the valve unplugged, apply vacuum to the engine-side port; it should hold steady. A purge valve that bleeds down lets the test vacuum escape and can also cause rough idle right after refueling.
Tools: Vacuum gauge
Smoke test the canister half
Feed smoke into the EVAP service port or the canister line with the vent shut valve closed. Watch the canister seams, hose ends and the vent valve body; small leaks here are often invisible without smoke.
Tools: Smoke machine, Flashlight
Run the EVAP function test
A scan tool with Honda functions can command the vent shut valve, purge valve and bypass solenoid and run the system's own leak test. That confirms the repair without waiting several days for the monitor to run on its own.
Tools: OBD-II scanner
Where the parts are
- 1Gas cap
- 2Charcoal canister
- 3Purge valve
- 4Vent valve
- 5Fuel pump
- 6Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace canister vent shut valve (DIY part) | Yes | $40–$120 |
| Replace canister vent shut valve at a shop | No | $150–$350 |
| Replace cracked EVAP hose on the canister side | No | $80–$250 |
| Replace purge control solenoid | No | $120–$300 |
| Replace charcoal canister | No | $300–$750 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Will fail
An active P1457 keeps the check engine light on, which fails an OBD-based smog or emissions inspection. After the repair, the EVAP monitor must also show complete; many states allow one incomplete monitor on newer cars, but check your state's rule before retesting.
Frequently asked questions
Will a new gas cap fix P1457?
Rarely. The gas cap sits on the tank side of Honda's split test, which is what P1456 covers. With P1457 the leak is almost always at the vent shut valve, canister or purge side hoses.
Why does my vent shut valve keep failing?
It lives under the car next to the canister, where road salt, water and mud reach it. The metal parts corrode and swell until the seal no longer closes. Some owners add a small splash guard or apply a protective coating to the new valve.
Can I replace the vent shut valve myself?
Usually yes. It's held by one or two bolts and a hose clamp, and the connector unplugs by hand. Rusty fasteners are the main obstacle, so soak them with penetrating oil and replace the small hose if it's brittle.
How long until the check engine light stays off?
The EVAP test needs a cold start, a fuel level roughly between a quarter and three quarters, and steady driving. It can take several days of normal use, or you can run the test right away with a capable scan tool.
Sources
- Manufacturer public service information (cross-checked)
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